2012 IEEE ICMM - proCampus GmbH

2012 IEEE ICMM 

IEEE INTERNATIONAL CONFERENCE ON MICROWAVE MAGNETICS 

Program & abstracts 


IEEE International Conference on Microwave Magnetics 2012 

Kaiserslautern, August 26-29, 2012 

University of Kaiserslautern 

MAGNETICS

www.icmm2012.de 

Herausgeber: 

TU Kaiserslautern 

Fachbereich Physik 

Postfach 3049 

67653 Kaiserslautern 

Tel.: (0631) 205-42 28 

hilleb@physik.uni-kl.de 

Layout und Druck: 

TU Kaiserslautern 

Hauptabteilung 5 

Abt. 5.6 Foto-Repro-Druck 

Fotos: 

Thomas Koziel 

proCampus GmbH

Welcome Address 

Dear Colleague, 

On behalf of the Organizing Committee it is my great pleasure to welcome you to the 2012 IEEE International 

Conference on Microwave Magnetics. This is now the third ICMM conference and, after the success of Fort Collins 

(2008) and Boston (2010), it is a privilege to be able to host the meeting in my home town of Kaiserslautern. 

I am extremely grateful to the Program Committee and the International Advisory Committee who have put together 

a scientific program which will showcase the very best, and the very latest, in six key areas of microwave magnetics: 

• RF, Microwave, and Millimeter Wave Devices 

• High Frequency Materials 

• Magnetization Dynamics and Relaxation 

• Nonlinear Phenomena 

• Magnon Spintronics and Caloritronics 

• Spin-Torque Oscillators 

Over the last four years ICMM has grown dramatically; a trend which is witness to the ever-expanding interest in our 

field, and gives us all the more reason to meet, to share our successes, and to exchange ideas. 

I look forward to what promises to be a very special few days. 

Burkard Hillebrands 

Chair, IEEE ICMM 2012

TAble of conTenTs 

International Advisory Committee ..................................................................................... 5 

Organizing Committee ...................................................................................................... 5 

Sponsors ........................................................................................................................... 6 

Conference Venue ............................................................................................................. 7 

Invitation to Conference Dinner ........................................................................................ 9 

General Information ........................................................................................................ 10 

Schedule ...........................................................................................................................13 

List of Posters ....................................................................................................................20 

Abstracts – Oral Contributions ...........................................................................................25 

Abstracts – Posters ............................................................................................................77 

List of Authors .................................................................................................................137 

Map of TU KL .........................................................................................................backpage 

3

InTernATIonAl AdvIsory commITTee 

Douglas J. Adam (Northrop Grumman STC, Baltimore, USA; ret.) 

Christian H. Back (Universität Regensburg, Germany) 

Zbigniew Celinski (University of Colorado, Colorado Springs, USA) 

Sergej O. Demokritov (Universität Münster, Germany) 

Thibaut Devolder (Université Paris-Sud and CNRS, France) 

Gerald F. Dionne (Massachusetts Institute of Technology, Boston, USA) 

Ron B. Goldfarb (National Institute of Standards and Technology NIST, Boulder, USA) 

Konstantin Gusliyenko (Universidad del País Vasco, Bilbao, Spain) 

Vincent G. Harris (Northeastern University, Boston, USA) 

Huahui He (Huazhong University of Science and Technology, China) 

Pavel Kabos (National Institute of Standards and Technology NIST, Boulder, USA) 

Boris A. Kalinikos (Saint Petersburg Electrotechnical University LETI, Russia) 

Andrei N. Slavin (Oakland University, USA) 

Nicolas Vukadinovic (Dassault Aviation, France) 

Mingzhong Wu (Colorado State University, Fort Collins, USA) 

Masahiro Yamaguchi (Tohoku University, Sendai, Japan) 

Arthur Yelon (École Polytechnique de Montréal, Canada) 

orgAnIzIng commITTee 

Martin Aeschlimann (University of Kaiserslautern) 

Andrii Chumak (University of Kaiserslautern) Publications 

Burkard Hillebrands (University of Kaiserslautern) General Chair 

Alexy Karenowska (University of Oxford) 

Oleksandr Serha (University of Kaiserslautern) Technical and Program Chair, Treasurer 

5

International Conference on Microwave Magnetics 2012 

6 

sponsors 


IEEE International Conference on Microwave Magnetics 2012 

A conference of the 

IEEE Magnetics Society 

MAGNETICS 

Financial support kindly provided by 

University of Kaiserslautern 

State Research Center for 

Optics and Material Sciences 

Singulus Technologies AG (Kahl, Germany) 

Sensitec GmbH (Lahnau, Germany) 

Organizational services by 

proCampus GmbH (Kaiserslautern)

conference venue 

The City of Kaiserslautern 

Kaiserslautern is an old city which can trace its roots as far back as the 9th century. The city’s name dates from the 

time of Emperor Friedrich Barbarossa; the ruins of a castle which he used as a hunting retreat still exist and can be 

visited. A modern landmark of Kaiserslautern is the Fritz-Walter-Stadium that holds more than 50,000 spectators and 

hosted several world championship games in 2006. 

Another attraction is Kaiserslautern’s Japanese garden 

(just north of city center, within walking distance). 

Founded within the framework of Kaiserslautern’s 

city partnership with Bunkyo-ku (Tokyo metropolitan 

area), it is among the largest and most beautiful parks 

of this kind in Europe. The artistically designed harmony 

of light and shadows, plants and stones, and water and 

paths invites its visitors to find energy and peace. 

Kaiserslautern sits close to the northern border of the 

Palatinate forest which is one of the largest natural 

forests in Europe and the area around Kaiserslautern is has more medieval castles per square mile than anywhere 

else in the world. Running along the eastern edge of the Palatinate forest is the upper Rhine valley, an area worldrenowned 

for its top class wineries. There are also plenty of opportunities for outdoor activities such as hiking, 

mountain biking, and golfing. 

7


8 

conference venue 

The University of Kaiserslautern 

Over the four decades since it was founded in 1970, TU Kaiserslautern 

has established a reputation for excellence among German universities— 

both for the quality of its research, and its undergraduate and graduate 

teaching—and has become internationally known for its strength in science 

and technology. In 2009, the university was among the few winners of the 

national competition “Exzellenz in der Lehre” for its concepts of education 

and promotion of students and young researchers following the principle of 

“Students as Partners”. 

At TU Kaiserslautern research and education are closely integrated; the university 

are part of several national and international research-oriented training networks 

including a federal Graduate School of Excellence. The Distance and Independent 

Studies Center (DISC) of TU Kaiserslautern is Germany’s second largest provider 

of graduate distance education. 

TU Kaiserslautern shares a modern campus with several other advanced research 

institutes including the Max Planck Institute for Software Systems, the Fraunhofer- 

Institut für Techno- und Wirtschaftsmathematik (ITWM), the Fraunhofer-Institut 

für Experimentelles Software Engineering (IESE), the Fraunhofer Institut für Physikalische 

Messtechnik (IPM), and the Deutsche Forschungszentrum für Künstliche 

Intelligenz (DFKI). 

Key data about TU Kaiserslautern (as of 2011) 

• 12,500 students in 102 study programs. 

• 158 tenured professors, 28 junior professors, 1,650 employees. 

• Third-party funding: 42 Mio € (2010). 

• 12 Academic Departments: Architecture, Biology, Business Studies and Economics, Chemistry, Civil 

Engineering, Computer Sciences, Electrical and Computer Engineering, Mathematics, Mechanical and 

Process Engineering, Physics, Regional and Environmental Planning, Social Sciences.

InvITATIon 

ConferenCe Dinner 

& 

Honorary SeSSion 

TueSDay, auguST 28, 2012 aT 19:15 

friTz-WalTer STaDium ConvenTion CenTer 

friTz-WalTer-STaDion – norDTribüne, friTz-WalTer-STraSSe 1, 

67663 KaiSerSlauTern, Tel. +49 (0)6 31 31 88 41 00 

aWarD Ceremony 

• 

a looK aHeaD To iCmm2014 

• 

magiC of ligHT, Spin, anD maTTer 

a SHuTTle buS To THe venue Will DeparT from THe ConferenCe venue aT 19:00 

aDDiTional TiCKeTS for THe Dinner Can be obTaineD aT THe ConferenCe reCepTion DeSK. 

9


10 

generAl InformATIon 

Internet Access 

In the area of the conference hall, a WLAN access point called “TU-KL_guest” has been set up for ICMM2012 

participants (username: icmm2012, Password: saexopeixi). 

In addition, the eduroam network is available throughout the campus to existing subscribers. 

Presentation Format 

Oral papers accepted for the conference will be presented using an LCD projector. Plenary talks will be 40 minutes 

plus 5 minutes for discussion, invited talks will 25 minutes plus 5 minutes for discussion and all other oral presentations, 

12 minutes, followed by 3 minutes of discussion. Please note that ONLY an LCD projector with a VGA input lead 

will be provided. Participants must bring their presentation on their own laptop computer together with a backup 

copy (Windows format) on a USB Drive in case of laptop failure. Please approach the technical service staff before 

your session to check the technical equipment for your presentation. 

For poster presentations the poster size must not exceed the DIN A0 vertical format (1189 mm high by 841 mm 

wide). The poster exhibition will take place in the foyer of building 42 in front of the conference lecture hall. Boards 

for hanging posters will be available on Monday morning. Each poster will be allocated a specific board (indicated by 

numbered markers). Presenting authors should be available for discussion (at their poster) during the poster session 

(Monday, August 27, 17:00-19:00) and it is suggested that posters are left on display throughout the conference. 

Public Transport 

A special shuttle bus (displaying the sign “Sonderfahrt”) will run in the mornings (Monday to Wednesday): 

08:15 Hotel Novotel 

08:25 Schillerplatz 

08:30 Stiftsplatz (next to Hotel SAKS) 

08:35 Hotel Zollamt 

08:45 TU Kaiserslautern (“Uni-Sporthalle”) 

A shuttle bus will also serve the conference dinner on Tuesday night at the Fritz-Walter Stadium Convention Center 

(Fritz-Walter-Stadion – Nordtribüne, Fritz-Walter-Straße 1, 67663 Kaiserslautern, Tel. 0631-3188-4100). This bus will 

leave from the Uni-Sporthalle bus stop at 19:00. No tickets are necessary for any of the shuttle services. 

On registration you will be issued with five tickets valid for travel on standard city bus routes. A map indicating 

all of Kaiserslautern’s bus services (which can also be found at http://www.swk-kl.de -> Busverkehr -> Fahrplan und 

Liniennetz with Fahrplan = time table, Liniennetzplan = map of bus lines) will also be provided. Buses are entered 

at the front and left by the back doors. Tickets are stamped upon entering the bus (typically using a machine near 

the driver’s booth). One ticket allows you to make a journey using a maximum of two consecutive buses (you should 

stamp the other side of the ticket on entering the second bus). 

If you have any unused bus tickets please return them to the reception desk at the end of the conference. The reception 

desk will also be able to help you should you require extra tickets.

Meals 

During coffee breaks an assortment of hot and cold drinks and light snacks will be available in front of the lecture 

hall. Lunch will be provided free of charge during the times indicated in the conference schedule in a designated area 

of the “Mensa” (building 32, opposite building 42, please follow the signs).You will be offered a choice between two 

three-course meals (one of them vegetarian) and drinks will be served at the table. You are also welcome to use the 

Mensa’s other facilities, e.g. the Cafeteria “Atrium”. Please note however that cash payments are only accepted in the 

Cafeteria and the free-flow service area (Wok/Grill) (no credit cards). 

Hors d’Oeuvres on Sunday and Bierstube on Monday will be served in the foyer in front of the conference lecture hall 

(building 42).The conference dinner with honorary session will take place in the conference center of the Fritz-Walter- 

Stadium. For further details, please turn to the invitation in this abstract and program book. 

Touristic Activities 

Information about touristic activities during and/or after the conference are available at the conference reception 

desk. We will be delighted to provide you with suggestions about how to best experience Kaiserslautern and the 

Pfälzerwald. 

A walking tour of the city will take place Tuesday, August 28 at 14:00. Please approach the conference reception desk 

for further information. 

directions sketch for the Fritz-Walter-Stadium 

Convention directions Center 

sketch 

please use car park east (Werner-Liebrich-Tor) 

approach to car park east: 

• coming from from the trainstation 

university Bremerstraße campus 

- from “11-Freunde-Kreisel” turn 

right in direction Schulzentrum, 

then turn immediately left into 

„zum Betztenberg“ 

- go straight on and drive past the 

stadium to your left 

- turn left at the crossroad 

• coming from Kantstraße 

Kantstraße, AGIP or 

or Novotel 

- turn right at AGIP petrol station 

into Fritz-Walter-Straße 

- follow the major road 

- car park next to the box office 

The entrance is tagged red. 

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Schedule 

13


Sunday, August 26, 2012 

18:00 – Check-in / Reception with Wine and Hors d‘Oeuvres 

21:00 

Monday, August 27, 2012 

09:00 Check-in 

09:45 Burkard Hillebrands 

Opening Address 

10:00 A01-P 

Bretislav Heinrich 

Spin pumping in ferro and ferri magnetic heterostructures 

Plenary Lecture 

Chair: Andrei N. Slavin 

10:45 Coffee Break 

Session 1 - Magnon Spintronics and Caloritronics I 

Chair: Sergej Demokritov 

11:15 A02-I 

Vincent Castel, Nynke Vlietstra, Jamal Ben Youssef, Bart van Wees 

Platinum thickness dependence of the inverse spin-Hall voltage from spin pumping in a hybrid YIG/Pt system 

Invited Lecture 

11:45 A03-I 

Yoshichika Otani 

Giant spin Hall effect induced in copper by doping small amount of impurities with large SO coupling 


12:15 A04-C 

Elisa Papa, Stewart E. Barnes, Jean-Philippe Ansermet 

Ferromagnetic resonance in the presence of a heat current 

12:30 A05-C 

Nikolay Polushkin 

Effects of electric current on band structure in magnonic crystals 

12:45 Lunch 

Session 2 - Magnetization Dynamics and Relaxation I 

Chair: Brett Heinrich 

14:00 A06-I 

Grégoire de Loubens 

Characterization and control of the dynamic dipolar coupling between magnetic nanodisks using MRFM 


14

14:30 A07-I 

Ulrich Hoeppe, Cristian Wolff, Hartmut Benner, Kurt Busch 

Controlling spontaneous emission in photonic crystals by ferromagnetic resonance 


15:00 A08-C 

Feng Guo, Lyubov Belova, Robert McMichael 

Spectroscopy and imaging of edge modes in Permalloy nanodisks 

by ferromagnetic resonance force microscopy 


Session 3 - Magnetization Dynamics and Relaxation II 

Chair: Grégoire de Loubens 

15:45 A09-C 

Lance DeLong, Vinayak Bhat, Justin Woods, Todd Hastings, Joseph Sklenar, John Ketterson 

Broad-band FMR study of ferromagnetic thin films patterned with antidot lattices 

16:00 A10-C 

Subhash Thota, Subrat Kumar Das, Ashok Kumar, Sambasivam Sangaraju, Byung Chun Choi 

Memory effects and relaxation dynamics of MnCo O nanocrystallites 

2 4 

16:15 A11-C 

Guru Venkat, Dasari Venkateswarlu, Rajeev S. Joshi, Hans Fangohr, P.S. Anil Kumar, Anil Prabhakar 

Spin wave dispersion in a permalloy ring structure using finite element micromagnetic simulations 

16:30 A12-C 

Yuriy Pogorelov, Andrey Timopheev, Nikolai Sobolev, Sergey Bunyaev, Susana Cardoso, 

Paulo Freitas, Gleb N. Kakazei 

Interlayer coupling in NiFe/CoFe/Cu/CoFe/MnIr spin-valves studied by ferromagnetic resonance 

16:45 A13-C 

Kim June-Seo, Mathias Kläui, Martin Stärk, M.S. Jungbum Yoon, 

Chun-Yeol You, Luis Lopez-Diaz, Eduardo Martinez 

Interaction between propagating spin-waves and domain walls on a ferromagnetic nanowire 

17:00 – POSTER SESSION and Bierstube 

19:00 

15


Tuesday, August 28, 2012 

09:00 B01-P 

Douglas J. Adam 

Magnetostatic wave frequency selective limiters 


Chair: Konstantin Guslienko 

Session 4 - RF, Microwave and Millimeter Wave Devices 

Chair: Sergei A. Nikitov 

09:45 B02-I 

Yat-Yin Au, Ehsan Ahmad, Mykola Dvornik, Oleksandr Dmytriiev, Toby Davison, Volodymyr Kruglyak 

Magnonic logic architectures driven by microwaves 


10:15 B03-I 

Zhijuan Su, Alexander Sokolov, Jianwei Wang, Yajie Chen, Anton Geiler, Lee Burns, Andrew Daigle, 

Carmine Vittoria, Vincent Harris 

Self-biased microstripline ferrite circulators 


10:45 B04-C 

Alexey Ustinov, Erkki Lahderanta 

A microwave nonlinear phase shifter based on forward volume spin waves 


Session 5 - Magnetization Dynamics and Relaxation III 

Chair: Denise Hinzke 

11:30 B05-I 

Ruslan Salikhov, Radu Abrudan, Frank Brüssing, Florin Radu, Kurt Westerholt, Ilgiz Garifullin, 

Hartmut Zabel 

Effect of spin pumping and domain wall induced coupling on configurational dependence of 

magnetization dynamics in spin valves 


12:00 B06-C 

Sergey Platonov, Ivan Lisenkov, Sergei A. Nikitov 

Anomalous Hall effect of magnons in inhomogeneous ferromagnetic media 

12:15 B07-C 

Guillermo Ortiz, Alberto Garcia, Jamal Ben Youssef, Biziere Nicolas, Fabrice Boust, Jean Francois Bobo, 

Etienne Snoeck, Nicolas Vukadinovic 

Broadband ferromagnetic resonance study of CO MnSi thin films: effect of the film thickness 

2 

12:30 B08-C 

Glade Sietsema, Michael Flatté 

Spin wave properties of two-dimensional magnetic superlattices 

12:45 Lunch 

Session 6 - High Frequency Materials 

Chair: Volodymyr Kruglyak 

14:00 B09-I 

Sergei A. Nikitov, Yury Filimonov, Yuri V. Khivintsev, Evgenii Pavlov, Valentin Sakharov, Sergey Vysotsky 

Spin-wave dynamics in lateral periodic and quasiperiodic magnetic micro- and nanostructures – magnonic crystals. 

16 

Invited Lecture

14:30 B10-I 

Masahiro Yamaguchi, Yasushi Endo, Sho Muroga, Makoto Nagata, Satoshi Tanaka 

Soft magnetic thin film application to suppress electromagnetic noise on LTE-class RFIC 


15:00 B11-C 

Mangui Han, Konstantin Rozanov, JunFeng Qin, Longjiang Deng 

Enhanced microwave permeability and mössbauer spectra of Fe-Si-Al flakes 

15:15 B12-C 

Kai-Hung Chi, Yun Zhu, Chen Tsai 

Two-dimensional magnonic crystal with periodic thickness variation in YIG layer for magnetostatic 

volume wave propagation 

15:30 B13-C 

Huseyin Kavas 

Magnetic nanometal coated polyacrynitrile textiles as microwave absorber 

15:45 B14-C 

Peiheng Zhou, Huibin Zhang, Haipeng Lu, Jianliang Xie, Longjiang Deng 

FeCoBSi thin film based magnetic structural materials for microwave application 

16:00 B15-C 

Julien Neige, Thomas Lepetit, Nicolas Malléjac, Anne-Lise Adenot-Engelvin, André Thiaville, 

Nicolas Vukadinovic 

Microwave permeability behaviour of FeNiMo flakes-polymer composite with an applied static field 

16:15 B16-C 

David Menard, Louis-Philippe Carignan 

Magnetic damping in ferromagnetic nanowire arrays 


Session 7 - Nonlinear Phenomena 

Chair: Thibaut Devolder 

17:15 B17-I 

Boris Kalinikos 

Tunable artificial multiferroic structures: Linear and nonlinear microwave properties. 


17:45 B18-I 

Sergey V. Grishin, Yurii P. Sharaevskii, Sergei A. Nikitov, Dmitrii V. Romanenko 

Generation of chaotic microwave pulses in ferromagnetic film ring oscillator under an external influence 


18:15 B19-C 

Thomas Sebastian, Philipp Pirro, Thomas Brächer, Alexander Serga, Takahide Kubota, Hiroshi 

Naganuma, Mikihiko Oogane, Yasuo Ando, Burkard Hillebrands 

Nonlinear emission of spin-wave caustics from an edge mode of a micro-structured Heusler waveguide 

18:30 B20-C 

Gennady Melkov, Denys Slobodianiuk, Vasyl Tiberkevich, Andrei Slavin 

Nonlinear ferromagnetic resonance in magnetic nanostructures having discrete spectrum of spin wave 

modes 

19:15 Conference Dinner and Honorary Session at Fritz-Walter-Stadium Convention Center (Kaiserslautern) 

17


Wednesday, August 29, 2012 

09:00 C01-P 

Andrei Slavin, Vasyl Tiberkevich 

Autonomous and non-autonomous dynamics of spin-torque oscillators: general theory and new developments 


Chair: Johan Åkerman 

Session 8 - Spin-torque oscillators I 

Chair: Robert McMichael 

09:45 C02-I 

Giovanni Carlotti 

Spatial profile of spin waves excited by a spin-torque oscillator and by coplanar waveguides 


10:15 C03-C 

Mauricio Manfrini, Joo-Von Kim, Sébastien Petit-Watelot, Ruben Otxoa, Claude Chappert, 

Win Van Roy, Laith Altimime, Jorge Kittl, Liesbet Lagae, Thibaut Devolder 

Transfering magnetic vortices between many spin torque oscillators 

10:30 C04-C 

Kerstin Bernert, Volker Sluka, Ciaran Fowley, Huadong Gan, Jürgen Fassbender, Alina M. Deac 

Switching voltages and back-hopping in magnetic tunnel junctions with different geometries 


Session 9 - Magnon Spintronics and Caloritronics II 

Chair: Yoshichika Otani 

11:15 C05-I 

Matthieu Bailleul 

Using spin waves to probe spin-polarized electron transport 


11:45 C06-I 

Denise Hinzke, Ulrike Ritzmann, Ulrich Nowak 

Domain wall dynamics and the magnonic spin Seebeck effect 


12:15 C07-C 

Vincent Laur, Patrick Queffelec, Faliniaina Rasoanoavy, Gor Lebedev, Bernard Viala, Mai Pham-Thi 

Evidence of a strong magnetoelectric effect in a FeCoB/PMN-PT bilayer at microwave frequencies 

12:30 C08-C 

Koji Sekiguchi, Taco Vader, Keisuke Yamada, Shunsuke Fukami, Nobuyuki Ishiwata, Soo-man Seo, 

Seo-won Lee, Kyung-jin Lee, Teruo Ono 

Attenuation of propagating spin wave induced by layered nanostructures 

12:45 Lunch 

18

Session 10 - Magnetization Dynamics and Relaxation IV 

Chair: Matthieu Bailleul 

14:00 C09-I 

Marie Barthelemy, Monica Sanches Piaia, Mircea Vomir, Michele Albrecht, Jean-Yves Bigot 

Coherent magnetization dynamics investigated with magneto-optical four wave mixing in a garnet film 


14:30 C10-C 

Hidekazu Kurebayashi, Dong Fang, Andrew Ferguson, Oleksandr Dzyapko, Vladislav Demidov, 

Sergej Demokritov 

Excitation of magnetic dynamics by the spin-orbit interaction 

14:45 C11-C 

Yuki Kawada, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando 

Spin torque vortex oscillation properties in CPP-GMR devices with perpendicular [Co/Pd]n spin injector 

15:00 C12-C 

Sabine Alebrand, Daniel Steil, Mirko Cinchetti, Martin Aeschlimann 

Revealing the significance of heating in the all-optical switching process 

15:15 C13-C 

Jiwan Kim, Mircea Vomir, Jean-Yves Bigot 

Ultrafast magneto-acoustics using femtosecond laser pulses 


Session 11 - Spin-torque oscillators II 

Chair: Giovanni Carlotti 

16:00 C14-I 

Sergej Demokritov, Vladislav E. Demidov 

Magnetization dynamics in micro-dots driven by magnetic field and spin-transfer torque 


16:30 C15-I 

Johan Åkerman, Majid Mohseni, Johan Persson, Sohrab Sani, T. N. Anh Nguyen, Sunjae Chung, 

Yevgen Pogoryelov, Pranaba Muduli, Alina M. Deac, Mark Hoefer 

Magnetic droplets in nano-contact spin torque oscillators with perpendicular anisotropy free layers 


17:00 C16-C 

Pranaba Muduli, Olle G. Heinonen, Johan Åkerman 

Origin and consequence of mode hopping in a magnetic tunnel junction based spin torque oscillator 

17:15 C17-C 

Stavros Komineas 

Frequency generation by a magnetic vortex-antivortex dipole in spin-polarized current 

17:30 Burkard Hillebrands 

Closing Remarks 

19


20 

Posters 

High Frequency Materials 

P01 Li Zhang, Peiheng Zhou, Mangui Han, Jianliang Xie, Longjiang Deng 

Double resonance behavior of FeCo/(FeCo)0.63(SiO2)0.37 multilayer on flexible substrates 

P02 Mangui Han, Ravi Hadimani, Longjiang Deng 

Microwave permeability of single cobalt nanotubes studied by the generalized Snoek’s law 

P03 Zo Raolison, Christophe Lefevre, Julien Neige, Anne-Lise Adenot-Engelvin, Geneviève Pourroy, 

Nicolas Vukadinovic 

Preparation and properties of silica coated Ni-Fe-Mo flakes composites 

P04 Mangui Han, Zhenhua Cao, Longjiang Deng 

Large intrinsic microwave permeability and microwave absorption properties of Z-type hexaferrites 

with CoZn substitution 

P05 Natalia Grigoryeva, Boris Kalinikos 

Normal mode theory for magnonic crystal waveguide 

P06 Biswanath Bhoi, N. Venkataramani, R. P. R. C. Aiyar, Shiva Prasad 

FMR and magnetic studies on polycrystalline YIG thin films deposited using pulsed laser 

P07 Aleksandra Trzaskowska 

The phonon-magnonic bandgaps in 1D magnonic crystals based on surface corrugated YIG 

P08 Zuzana Kozakova, Ivo Kuritka, Vladimir Babayan 

Synthesis and properties of magnetic nanoparticles for high frequency materials 

P09 Julián González, Mihail Ipatov, Lorena González, Javier Garcia, Alexander Chizhik, 

Lourdes Dominguez, Valentina Zhukova, Arkady Zhukov, Blanca Hernando 

Induced giant magnetoimpedance effect by current annealing in ultra thin Co-based amorphous ribbons 

Magnetization Dynamics and Relaxation 

P10 Subhash Thota, Kiran Singh, Charls Simon, Wilfrid Prelier 

Dielectric and AC-magnetic response of the complex spin ordering processes in Mn O 3 4 

P11 Crosby Chang, Mikhail Kostylev, Adekunle Adeyeye, Matthieu Bailleul, Sergey Samarin 

Ferromagnetic resonance of a magnetic nanostripe array using a micron-sized coplanar probe 

P12 Thomas Bose, Steffen Trimper 

Nonlocal feedback in ferromagnetic resonance 

P13 Alexander Kamantsev, Victor Koledov, Vladimir Shavrov 

Thermodynamic and relaxation processes in phase transitions in advanced magnetocaloric materials 

P14 Michal Mruczkiewicz, Maciej Krawczyk, Valentine K. Sakharov, Yuri V. Khivintsev, Yuri Filimonov, 

Sergei A. Nikitov 

Standing spin waves in 1D Co/Py magnonic crystals 

P15 Nikhil Kumar, Anil Prabhakar 

Spin wave dispersion in striped magnonic waveguide 

P16 Nikolay Polushkin 

Nondiffractive origin of bandgaps in periodic lattices

P17 Andreas Neudert, Rantej Bali, Mikhail Kostylev, Adekunle Adeyeye, Florian M. Römer, 

Kai Wagner, Michael Farle, Kilian Lenz, Jürgen Lindner, Jürgen Fassbender 

Magnetization dynamics of Co antidot lattices 

P18 Vladislav Demidov, Sergej Demokritov, Mikhail Kostylev 

Control of spin-wave phase and wavelength in microscopic magnonic waveguides 

P19 Andrii Chumak, Vitaliy Vasyuchka, Alexander Serga, Mikhail Kostylev, Vasyl Tiberkevich, 


Storage-recovery phenomenon in a magnonic crystal 

P20 Sergeiy Mankovskyy, Hubert Ebert, Diemo Koedderitzsch 

Ab-initio calculation of the Gilbert damping parameter via linear response formalism 

P21 Matthieu Bailleul 

Shielding of the electromagnetic field of a coplanar waveguide by a metal film: implications 

for broadband ferromagnetic resonance measurements 

P22 Thomas Brächer, Philipp Pirro, Björn Obry, Alexander Serga, Britta Leven, Burkard Hillebrands 

Mode selective parametric excitation of spin waves in a Ni 81 Fe 19 microstripe 

P23 Rohan Adur, Inhee Lee, Yuri Obukhov, Christine Hamann, Jeffrey McCord, Denis V. Pelekhov, 

P. Chris Hammel 

Scanning probe ferromagnetic resonance imaging of stripe patterned exchange bias film 

P24 Milan Agrawal, Hiroshi Idzuchi, Yasuhiro Fukuma, Alexander Serga, Yoshichika Otani, 


Spin dynamics excitation in nonlocal spin-valves 

P25 Gloria Rodríguez Aranda, Gleb N. Kakazei, Sergey A. Bunyaev, Vladimir A. Golub, Elena V. 

Tartakovskaya, Andrii V. Chumak, Alexander Serga, Burkard Hillebrands, Konstantin Gusliyenko 

Field orientation dependence of dynamical magnetization pinning of the main ferromagnetic resonance 

mode in a circular dot 

P26 Michael Körner, Kilian Lenz, Andreas Neudert, Pedro Landeros, Maciej Oskar Liedke, 

Jürgen Lindner, Jürgen Fassbender 

Magnetic relaxation in one-dimensional magnonic crystals 

P27 Katrin Vogt, Helmut Schultheiss, Shikha Jain, John E. Pearson, Axel Hoffmann, Samuel D. Bader, 


Bending spin waves around the corner 

P28 Martin Wahler, Nico Homonnay, Bastian Büttner, Hans-Helmuth Blaschek, 

Christian Eisenschmidt, Georg Schmidt 

Magnetization dynamics in an array of ferromagnetic oxide nanostructures 

P29 Yuriy Pogorelov, Mariana Proença, Célia Sousa, João Ventura, João Pedro Araújo, 

Manuel Vasquez, Andrey Timopheev, Nikolai Sobolev, Gleb N. Kakazei 

Comparative study on magnetic nanowire and nanotube arrays by ferromagnetic resonance 

P30 Roberta Dutra de Oliveira Pinto, Diego Ernesto González-Chávez, Tatiana Lisboa Marcondes, 

Wagner de Oliveira da Rosa, Rubem Luis Sommer 

Splitting of FMR dispersion relation in NiFe/IrMn/Ta/NiFe spin-valve-like 

21


22 

P31 Diego Ernesto González-Chávez, Roberta Dutra de Oliveira Pinto, Tatiana Lisboa Marcondes, 

Rubem Luis Sommer 

Broadband ferromagnetic resonance studies in NiFe/X (X =Cu, Ag, Ta) multilayers 

P32 Ryszard Gieniusz, Vladimir Bessonov, Urszula Guzowska, Marek Kisielewski, Henning Ulrichs, 

Alex Stognii, Andrzej Maziewski 

Magnetostatic spin waves diffraction on antidots in yttrium iron garnet films 

P33 Jean-Yves Chauleau, Hans Bauer, Georg Woltersdorf, Christian Back 

Current-induced spinwave Doppler shift study by time-resolved scanning Kerr microscopy 

P34 Katrin Vogt, Oksana Sukhostavets, Helmut Schultheiss, Bjorn Obry, Philipp Pirro, Alexander 

Serga, Thomas Sebastian, Julian M. Gonzalez, Konstantin Y. Guslienko, Burkard Hillebrands 

Optical detection of vortex spin-wave eigenmodes in micron sized ferromagnetic circular dots 

Magnon Spintronics and Caloritronics 

P35 Dmytro Bozhko, Oleksandr Talalaevskij, Gennadii Melkov, Volodymyr Malyshev, 

Yurij Koblyanskij, Andrii V. Chumak, Alexander A. Serga, Burkard Hillebrands, Andrei Slavin 

Spin-Hall effect influence on ferromagnetic resonance in Pt-YIG structures 

P36 Andreas Kehlberger, René Röser, Gerhard Jakob, Ulrike Ritzmann, Ulrich Nowak, Mathias Kläui 

Thermally excited magnonic spin current coherence length probed by the longitudinal spin-Seebeck 

effect in YIG 

P37 Thomas Langner, Björn Obry, Thomas Brächer, Philipp Pirro, Katrin Vogt, Alexander Serga, 

Britta Leven, Burkard Hillebrands 

Spin wave resonance in Ni 81 Fe 19 microstripes containing a mechanical gap 

P38 Matthias Benjamin Jungfleisch, Andrii V. Chumak, Alexander Serga, Roland Neb, 

Dmytro Bozhko, Vasyl Tiberkevich, Burkard Hillebrands 

Direct detection of magnon spin transport by the inverse spin Hall effect 

P39 Vitaliy Vasyuchka, Alexander Serga, Andrii V. Chumak, Burkard Hillebrands 

Magnon mediated heat transport in a magnetic insulator 

P40 Alexander Serga, Milan Agrawal, Vitaliy Vasyuchka, Gennady Melkov, Burkard Hillebrands 

Magnon temperature measurements in magnetic insulators 

P41 Björn Obry, Vitaliy Vasyuchka, Andrii V. Chumak, Alexander Serga Burkard Hillebrands 

Spin wave propagation and transformation in a thermal gradient

Nonlinear Phenomena 

P42 Nynke Vlietstra, Vincent Castel, Jamal Ben Youssef, Bart van Wees 

Spin-current emission by spin pumping in a thin film YIG/Pt system: Frequency dependence 

P43 Alexey Ustinov, Boris Kalinikos, Vladislav Demidov, Sergej Demokritov 

Secondary self-modulation instability of microwave spin waves in ferromagnetic films 

RF, Microwave and Millimeter Wave Devices 

P44 Takashi Yoshikawa 

HEMS performed by a sensor network having an effectively wireless power supply 

P45 Xiong Lin, Wang Xiaoguang, Deng Longjiang 

Design of a miniaturized X-band substrate integrated waveguide circulator 

P46 Ourabia Malika 

Modeling and simulation of passive planar structures 

P47 Arman Afsari, Masoud Movahhedi 

A modified wavelet-based meshless method for lossy magnetic dielectrics at microwave frequencies 

P48 Lorenzo Fallarino, Marco Madami, Georg Dürr, Dirk Grundler, Gianluca Gubbiotti, Silvia Tacchi, 


Propagation of spin waves excited by a microwave current: a combined phase-sensitive micro-focused 

Brillouin light scattering and micromagnetic study 

P49 Ousama Abu Safia, Larbi Talbi, Khelifa Hettak 

A new class of artificial magnetic materials based on a modified uniplanar series resonator and their 

implementation in original applications 

P50 Yosuke Obinata, Megumi Yuki, Makoto Sonehara, Yutaka Kuramoto, Kunihiko Suzuki, 

Kenji Ikeda, Toshiro Sato 

A possibility of tunable soft magnetic inductive device using bias magnetic field of a hard magnetic film 

magnetized by pulsed-current method 

P51 Niranchanan Suntheralingam, Imtiaz Khairuddin, Ivor Morgan, Harkanwal Deep, Colin McLaren 

Enhanced high power 360 degree ferrite phase shifter for beam steering applications at Ka-band 

P52 Manjeet Ahlawat, R.S. Shinde 

Design and simulation of 505.8 MHz strip line ferrite circulator for Indus 2 

P53 Ayobami Iji 

SOI CMOS LNA for Implantable WBANs 

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24 

Spin-Torque Oscillators 

P54 Elmer Monteblanco, Daria Gusakova, Felipe Garcia Sanchez, Liliana Buda-Prejbeanu, 

Alex Jenkins, Ursula Ebels, Marie-Claire Cyrille, Bernard Dieny 

Spin torque driven excitations in synthetic antiferromagnets 

P55 Alex Jenkins, Bernard Rodmacq, Ursula Ebels, Marie-Claire Cyrille, Michael Quinsat, Juan Sierra, 

Betrand Delaet, Bernard Dieny 

Full phase diagram of spin torque oscillators with perpendicular polariser 

P56 Yevgen Pogoryelov, Sohrab Sani, Majid Mohseni, Johan Persson, Ezio Iacocca, Johan Åkerman 

Double-mode vortex dynamics in nanocontact spin-torque oscillators 

P57 Randy Dumas, Stefano Bonetti, Ezio Iacocca, Sohrab Sani, Majid Mohseni, Anders Eklund, 

Johan Persson, Olle G. Heinonen, Johan Åkerman 

Consequences of the Oersted field induced asymmetric energy landscape in nanocontact spin torque 

oscillators 

P58 Philipp Dürrenfeld, Pranaba Muduli, Johan Åkerman 

Parametric excitation in a magnetic tunnel junction-based spin torque oscillator 

P59 Vladislav Demidov, Henning Ulrichs, Sergej Demokritov, Sergei Urazhdin 

Spin-torque nano-emitters for magnonic applications

ABSTRAcTS – Oral contributions 

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26 

Plenary Lecture A01-P 

Spin pumping in ferro and ferri magnetic heterostructures 

Bretislav Heinrich 

Department of Physics, Simon Fraser University, Burnaby, V5A 1S6 BC, Canada 

Spin pumping studies in ultrathin magnetic heterostructures started by Y. Tserkovnyak , Brataas, and Bauer in their 

seminal paper [1]. It was shown that a peristaltic spin pumping can be generated by spin dynamics at the ferromagnet 

(FM)/normal metal (NM) interface and its strength is proportional to the spin mixing conductance gmix. I will then 

briefly describe history of experiments demonstrating that the coherent spin currents generated by rf field lead to 

an enhancement and de-enhancement of magnetic damping (Ferromagnetic Resonance (FMR) linewidth) and lead 

to rf excitations in magnetic heterostructures. The recent spin pumping studies in Fe/Au,Ag,Pd/Fe(001) structures 

allowed one to investigate the spin transport in NM [2]. We found that the electron spin flip scattering in Au is 

governed by phonons and is independent on electron momentum diffuse scattering at interfaces [3]. Spin pumping 

in Fe/Au,Ag/Pd/Fe(001) structures indicate that the Au,Ag/Pd interface leads to an appreciable spin current reflection. 

Recently attention has turned to developing ideas and systems where Spin Transfer Torque (STT) can be achieved by 

pure spin currents. A newly emerging field called spin caloritronics addresses the generation of a spin currents by a 

thermal gradient using magnetic insulators (MI) [4]. In our recent studies we investigated the spin pumping at the 

YIG/Au interface using FMR. The spin mixing conductance at an untreated YIG/Au interface was found to be, 

gmix = 1.1×10 14 /cm 2 [5]. A five fold time increase in spin pumping, gmix = 5.2×10 14 /cm 2 , was achieved by using a low 

energy Ar ion etching [6], it compares well with that at the Fe/Au interface, gmix = 1.1×10 15 /cm 2 . 

References 

[1] Y. Tserkovnyak at al., Phys. Rev. Lett. 88, 117601 (2002). 

[2] B. Kardasz and B. Heinrich, Phys. Rev. B 81, 94409 (2010). 

[3] E. Montoya et al. J. Appl. Phys. 111, 07C512 (2012). 

[4] J. C. Slonczewski Phys. Rev. B 82, 54403 (2010). 

[5] B. Heinrich et al. Phys. Rev. Lett. 107, 066604 (2011). 

[6] C. Burrowes et al., Appl. Phys. Lett. 100, 092403 (2012). 

bheinric@sfu.ca

Magnon Spintronics and caloritronics A02-I 


Platinum thickness dependence of the inverse spin-Hall voltage from spin pumping 

in a hybrid YIG/Pt system 

Vincent Castel 1 , Nynke Vlietstra 1 , Jamal Ben Youssef 2 , Bart van Wees 1 

1 Zernike Institute for Advanced Materials and Department of Physics, University of Groningen, 9747 AG Groningen, 

Netherlands 

2Laboratoire de Magnétisme de Bretagne, Université de Bretagne Occidentale, 29285 Brest, France 

Recently in the field of spintronics, spin transfer torque and spin pumping phenomena in a hybrid ferromagnetic insulator 

(Yttrium Iron Garnet: YIG)/normal metal (Platinum: Pt) system have been demonstrated by Y. Kajiwara et al. [1]. Since this 

observation, the actuation, detection and control of the magnetization and spin currents in such systems have attracted much 

attention from both theoretical and experimental point of view. 

Spin pumping in a ferromagnetic (NiFe)/normal metal system has been intensively studied as a function of the stoichiometric 

ratio between nickel and iron atoms, the spin current detector material, and the ferromagnet dimensions. Only a few research 

groups [2, 3] have investigated experimentally and theoretically the dc voltage emission, induced by inverse spin-Hall effect 

(ISHE), in a NiFe/Pt system as function of the spin current detector and the ferromagnetic materials thickness, at a fixed microwave 

frequency. To date, no systematic studies of the spin/charge (charge/spin) conversion in a YIG/Pt system have been 

presented as function of the Pt thickness. 

We will present the Pt thickness dependence of the dc voltage in a hybrid system YIG/Pt actuated at the ferromagnetic resonance 

condition for different frequencies (0.1 until 7 GHz) and rf power (0.25 until 70 mW). 

The insulator materials consists of a single-crystal Y Fe O (YIG: 200 nm) (111) films grown by liquid phase epitaxy (LPE). The 

3 5 12 

Pt area has been patterned by electron beam lithography (EBL). We have prepared nine samples between 2 nm until 114 nm 

of Pt. By decreasing the Pt thickness (enhancement of the resistance of the Pt stripe) we are able to detect a dc voltage (at the 

resonant condition) of 55, 20.8, and 9.04 µV at 1, 3, and 6 GHz respectively for a Pt thickness of 6 nm and a RF microwave power 

of 63 mW.This strong enhancement (a factor of 70 between 6 and 114 nm of Pt) permits also to perform measurements at very 

low RF power, lower than 250 µW. Nevertheless, the Pt thickness dependence of the dc voltage is not obvious. We will discuss 

of the strong enhancement observed for the thinner layers of Pt, the frequency and rf power dependence of the dc voltage. 

References 

[1] Y. Kajiwara, K. Harii, S. Takahashi, J. Ohe, K. Uchida, M. Mizuguchi, H. Umezawa, H. Kawai, K. Ando, K. Takanashi, 

S. Maekawa, and E. Saitoh, Nature 464, 262 (2010). 

[2] A. Azevedo, L. H. Vilela-Leao, R. L. Rodriguez-Suarez, A. F. Lacerda Santos, and S. M. Rezende, Phys. Rev. B 83, 

144402 (2011). 

[3] H. Nakayama, K. Ando, K. Harii, T. Yoshino, R. Takahashi, Y. Kajiwara, K. Uchida, Y. Fujikawa, and E. Saitoh, Phys. 

Rev. B 85, 144408 (2012). 

v.m.castel@rug.nl 

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28 

Magnon Spintronics and caloritronics A03-I 


Giant spin Hall effect induced in copper by doping small amount of impurities 

with large SO coupling 

Yoshichika Otani 

University of Tokyo, 277-8581 Kashiwa, Japan 

The performance of spintronic behaviors including spin Seebeck and Peltier effects rely on efficient conversion between 

charge and pure spin currents, flow of spins without net charge. This may lead to low energy consumption or 

energy harvesting devices for next generation, and thus well explains a current great deal of interest in the spin Hall 

effects (SHE). 

A large spin Hall (SH) angle, i.e. a large conversion yield of charge to spin currents, is an indispensable prerequisite 

for practical applications. Here we demonstrate measurements of the very large SHE and inverse SHE induced by Bi 

impurities in Cu. Our data analyses based both on the classical 1D model of previous SHE studies and a 3D finite 

element treatment of spin transport yielded large SH angles of -0.12 for the 1D and -024 for the 3D models.The angle 

is definitely larger in 3D. Such a difference between 1D and 3D models is not surprising since the 3D model can treat 

more accurately the unavoidable approximations of the 1D model. 

There are two main conclusions. First the 3D treatment of spin accumulation and transport is effective for the spintronic 

devices based on increasingly more complex structures. Secondly our experimental and theoretical results show 

that an SHE much larger than what had been observed before can be obtained by doping a simple metal, copper, with 

impurities of large SO coupling, bismuth, and probably also other heavy elements like lead. Harnessing the SHE to 

produce or detect spin currents will be probably more and more used in novel generations of spintronic devices not 

necessarily based on magnetic materials. 

yotani@issp.u-tokyo.ac.jp

Magnon Spintronics and caloritronics A04-c 

Ferromagnetic resonance in the presence of a heat current 

Elisa Papa 1 , Stewart E. Barnes 2 , Jean-Philippe Ansermet 1 

1 Ecole Polytechnique Fédérale de Lausanne,Institut de Physique de la Matière Condensée, 1015 Lausanne, 

Switzerland 

2 University of Miami, Coral Gables, FL 33124, USA 

We explore the magnetization dynamics of a ferromagnetic system subjected to an in-plane temperature gradient. 

For this purpose, local ferromagnetic resonance studies at 4 GHz are performed on Yittrium Iron Garnet (YIG) – 

Y 3 Fe 2 (FeO 4 ) 3 – both in polycrystalline and single crystal form, in presence of a heat current. Our motivation for this 

work is the attention developed over the recent years for the Spin Seebeck effect [1]. 

The YIG samples studied have surface dimensions of 10 mm × 2 mm.The polycrystalline slab used is 0.1 mm thick and 

free-standing while the single crystal specimen is only 0.020 mm thick and is glued onto a glass substrate. A tempe- 

rature gradient of the order of 20 K/cm is applied as in the well-known Spin Seebeck geometry.This experiment offers 

a direct observation of the dynamic response of an insulating ferromagnet to an applied temperature bias through an 

investigation which is independent of any transport measurement and is free of electrical contacts. 

By monitoring the magnetostatic modes of YIG excited and detected at a local level using a loop probe with a diameter 

of 0.05 mm, we observe that the magnetization in both polycrystalline and single crystal YIG is responsive to the 

heat current generated by a temperature gradient. An evident effect is in fact seen on specific magnetostatic modes 

of the ferromagnetic spectrum of the sample under study. From the measurements taken on the thinner single crystal 

specimen for different orientations of the coil with respect to the YIG specimen and different sample-probe distances, 

it is possible to recognize the excited magnetostatic modes and assess which modes couple to the temperature 

gradient. 

References 

[1] K. Uchida et al., Nature 455, 778 (2008). 

elisa.papa@epfl.ch 

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30 

Magnon Spintronics and caloritronics A05-c 

Effects of electric current on band structure in magnonic crystals 


Instituto Superior Tecnico, 1049-001 Lisbon, Portugal 

Various effects associated with complementary process of so-called spin transfer torques, that effectively provide 

manipulation of the nanomagnetic properties, are currently of central importance in the field of spintronics. We find 

the robust effects of dc current on the magnonic band structure in magnetic periodic systems [magnonic crystals 

(MC´s)] where the saturation magnetization is modulated along a one of lateral directions [1]. By numerical solving 

the Landau-Lifshitz-Gilbert equation added by the diffusion term, we show that the MC gap can be shifted by current 

(108-109 A/cm2 ) passed across the MC along the periodicity direction. This shift is comparable to the total band for 

spin-wave (SW) excitation (~10 GHz) and is accompanied by the change in the effective MC period owing to the 

Doppler-shifted frequency of the spin wave. The SW Doppler can be much larger than that for other kinds of waves 

because of the smallness of SW phase velocity. Another effect we observe is the current-induced generation of new 

SW modes that provide arising additional bandgaps inside the Brillouin zones. A deeper understanding of the latter 

effect can be achieved by analyzing the origin of the MC bandgaps in the near-field configuration of the excitation 

source used in these considerations. 

Work was supported by the Portuguese Foundation for Science and Technology via research grant PTDC/ 

FIS/121588/2010. 

References 

[1] N. I. Polushkin, Appl. Phys. Lett. 99, 182502 (2011); ibid. 99, 229904 (2011). 

nipolushkin@fc.ul.pt

Magnetization dynamics and Relaxation A06-I 


Characterization and control of the dynamic dipolar coupling between 

magnetic nanodisks using MRFM 

Grégoire de Loubens 

CEA Saclay, Service de Physique de l‘Etat Condensé, 91191 Gif-sur-Yvette, France 

Arrays of magnetic nanostructures are expected to offer new functionalities to future microwave devices. In these arrays, 

the dipolar interaction between elements plays a key role. For instance, it is responsible for some collective modes which 

can be excited in magnonic crystals [1]. It could also be an efficient mechanism to synchronize arrays of spin transfer nanooscillators 

(STNOs), which is required to increase their emitted microwave power and to improve their phase noise [2,3]. 

Moreover, the dipolar interaction between the different magnetic layers of an individual STNO also influences its microwave 

properties [4,5]. 

We study two basic systems of nanodisks in dipolar interaction. The first one is the STNO archetype composed of two 

magnetic nanodisks on top of each other, and separated by a normal metal spacer. The second one is composed of several 

magnetic nanodisks which are closely separated laterally. In order to characterize the dipolar interaction between these 

individual nanodisks, we employ a magnetic resonance force microscope (MRFM [6]), in which a magnetic sphere attached 

at the end of a very soft cantilever is used to probe the magnetization dynamics in nanostructures. 

In the first system of investigation, we carefully identify the spin-wave (SW) eigen-modes when the bias magnetic field is applied 

exactly along the normal of the nanodisks. In this case, the observed SW spectrum critically depends on the method of 

excitation.While the spatially uniform microwave magnetic field excites only the axially symmetric modes having azimuthal 

index l = 0, the microwave current flowing through the STNO, creating a circular microwave Oersted field, excites only the 

modes having index l = +1. Experimental spectra are compared to theoretical prediction using both analytical and numerical 

calculations, in which the influence of the dynamic dipolar coupling between the STNO magnetic layers is analyzed [4]. 

In the second system, we perform a quantitative experimental study of dipolarly coupled SW dynamics in two closely 

separated nanodisks. In fact, the coupling strength can be continuously controlled and monitored with MRFM. For this, we 

take advantage of the magnetic field gradient from the MRFM probe to differentially tune the resonance frequencies of the 

adjacent nanodisks.While scanning the MRFM probe above the nanodisks, a series of SW spectra is acquired.The dynamic 

dipolar interaction is revealed by the frequency anti-crossing and by the hybridization of the coupled SW modes. We will 

also discuss similar experiments, where the MRFM probe strayfield is used to control the coupling between the gyrotropic 

modes of vortex-state nanodisks [7]. 

References 

[1] V.V. Kruglyak, S.O. Demokritov, G. Grundler, J. Phys. D: Appl. Phys., 43, 264001 (2010). 

[2] A. Slavin and V. Tiberkevich, IEEE Trans. Magn., 45, 1875-1918 (2009). 

[3] A. Hamadeh, et al., Phys. Rev. B 85, 140408 (2012). 

[4] V. Naletov, et al., Phys. Rev. B 84, 224423 (2011). 

[5] N. Locatelli, et al., Appl. Phys. Lett. 98, 062501 (2011). 

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32 

Magnetization dynamics and Relaxation A07-I 


Controlling spontaneous emission in photonic crystals by ferromagnetic resonance 

Ulrich Hoeppe 1 , Cristian Wolff 2 , Hartmut Benner 3 , Kurt Busch 4 

1 Technische Hochschule Mittelhessen, 61169 Friedberg, Germany 

2 Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany 

3 Institut für Festkörperphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany 

4 Humboldt-Universität zu Berlin, Institut für Physik, Theoretical Optics & Photonics Group, 12489 Berlin, Germany 

The radiation dynamics of a magnetic dipole located inside a photonic crystal has been considered as an analogue 

for optical emission of a point-like dielectric emitter in such a crystal. We have ex-perimentally realized this situation 

by fixing a single crystal yttrium iron garnet (YIG) sphere of 1.7 mm diameter inside a photonic crystal consisting of 

dielectric alumina rods. These rods form a woodpile structure of size 16 × 16 × 6 cm³. The photonic crystal shows 

a band gap at microwave frequencies from 12.9 to 14.3 GHz which calculated and verified from the transmission 

characteristics of the crystal. The radiation feedback [1] of the YIG sphere was probed by ferromagnetic resonance 

ex-periments covering a broad frequency range from 8 to 17 GHz. While outside the band gap the radiation-induced 

linewidth amounts up to 30 Oe it is almost complete suppressed within the gap. From the full analysis of linewidth 

and resonance shift we could clearly proof the non-Markovian character of the radiation dynamics at the edges of the 

gap as expected from theory [2]. The experimental control of spontaneous emission, as realized in our experiment, 

could be a first promising step towards future optical applications in low threshold lasers, highly efficient light emitting 

diodes or photovoltaic solar modules. 

References 

[1] R. W. Sanders, D. Paquette, V. Jaccarino, and S. M. Rezende, Phys. Rev. B 10, 132 (1974). 

[2] U. Hoeppe, C. Wolff, J. Küchenmeister, J. Niegemann, M. Drescher, H. Benner, and K. Busch, 

Phys. Rev. Lett. 108, 043603 (2012). 

ulrich.hoeppe@mnd.thm.de

Magnetization dynamics and Relaxation A08-c 

Spectroscopy and imaging of edge modes in Permalloy nanodisks by ferromagnetic 

resonance force microscopy 

Feng Guo 1 , Lyubov Belova 2 , Robert McMichael 1 

1 Center for Nanoscale Science andTechnology, National Institute of Standards andTechnology, Gaithersburg, MD 20899, USA 

2 Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm, 10044 Stockhom, Sweden 

We report ferromagnetic resonance force microscopy (FMRFM) of normal modes of in-plane magnetized, 25 nm thick 

Permalloy disks with diameters ranging from 100 nm to 750 nm. The modes, which are imaged with resolution on the order 

of 100 nm, include center modes and multiple edge modes, with up to 4 edge modes detected at each pole of the largest 

disk, and a single mode detected in the 100 nm disk. Many of the features of the measured spectra and images agree well 

with the predictions of micromagnetic modeling, including the spectral intensity and position of modes in the series of edge 

modes and the number of detected edge modes as a function of disk diameter. However, the model predicts edge mode 

resonance fields (frequencies) that generally are higher (lower) than the measured edge mode resonances, a significant 

difference that we attribute to differences between the actual film edge properties and the idealized edge properties of 

the model. In the 500 nm disk, the inhomogeneity of the disk edge properties is highlighted by measuring the edge mode 

resonances as a function of applied field angle in the plane of the film. The fundamental edge mode resonance, with 

maximum amplitude closest to the edge of the film exhibits a large asymmetry while the center mode resonance is nearly 

isotropic. 

These measurements represent a significant improvement in the sensitivity and resolution of the FMRFM instrument that 

is largely due to refinement of the magnetic cantilever tip. In contrast to previous generations which featured tips with 

diameters of 500 nm or 1000 nm, the tip used in these measurements is a 100 nm hemisphere of 74% Co (with carbon 

& oxygen) deposited by electron beam induced decomposition. This smaller tip, with correspondingly smaller stray fields, 

produces only weak perturbation of the sample resonances and allows the tip to be placed closer to the sample. For the 

100 nm disk, we achieve a signal to noise ratio of approximately 20:1 with 1 s integration time. 

rmcmichael@nist.gov 

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34 


Broad-band FMR study of ferromagnetic thin films patterned with antidot lattices 

Lance DeLong 1 , Vinayak Bhat 1 , Justin Woods 1 , Todd Hastings 2 , Joseph Sklenar 3 , John Ketterson 3 

1 University of Kentucky, Department of Physics and Astronomy, Lexington, KY 40506-0055, USA 

2 University of Kentucky, Department of Electrical and Computer Engineering, Lexington, KY 40506-0046, USA 

3 Northwestern University, Department of Physics and Astronomy, Evanston, IL 60208-3112, USA 

We have performed broad-band (10 MHz -14 GHz) ferromagnetic resonance (FMR) measurements on permalloy 

thin films patterned with square lattices of antidots (circular-, square- and diamond-shaped) of variable size and 

separation. The FMR spectra are strongly affected by the geometry of the antidot lattice (ADL). Moreover, we observe 

remarkably reproducible mode structures in the low-frequency, magnetic reversal regime; this is surprising, given that 

hysteretic domain wall (DW) evolution generates unsaturated, disordered magnetization textures in unpatterned 

films at low applied DC fields. These observations lead us to conclude the reproducible behavior of the low-field 

modes is caused by pinning of DW textures by antidot edges, as is verified by our micromagnetic simulations. The 

field, frequency and angular dependences of the observed modes (some not previously reported) are also in good 

agreement with our simulations. Our simulations also display magnetic vortex and antivortex generation at low 

applied magnetic fields, a phenomenon which has not been well studied in the case of antidot lattices. The simulated 

spatial distributions of resonant absorption at observed FMR frequencies strongly suggest DW pinning by the ADL 

also controls the localization and propagation of modes along various symmetry directions of the ADL. These findings 

have important implications for the control of magnetic reversal in patterned FM thin films. 

delong@pa.uky.edu


Memory effects and relaxation dynamics of MnCo 2 O 4 nanocrystallites 

Subhash Thota 1 , Subrat Kumar Das 1 , Ashok Kumar 2 , Sambasivam Sangaraju 3 , Byung Chun Choi 3 

1 1Indian Institute of Technology Guwahati, 781039 Guwahati, India 

2 Virginia Tech, Center for Energy Harvesting Materials and Systems (CEHMS), Blacksburg,VA 24061, USA 

3 Department of Physics, Pukyong National University, 608 737 Busan, South Korea 

We present a detailed analysis of the time decay of magnetization (M) and ac-magnetic susceptibility (χ ac ) of hexagonal- 

shaped MnCo 2 O 4 nanocrystals of size 28 nm. The temperature (T) and magnetic field (H) dependence of the magnetization 

yields ferromagnetic ordering with Curie temperature T C = 176.4 K. Cooling in the presence of magnetic field results in a re- 

latively large ferromagnetic moment with zero-field-cooled and field-cooled magnetization curves (M ZFC and M FC ) bifurcate 

at an irreversibility point 169 K. The cusp in the M ZFC and the features observed in the low-temperature regime indicate the 

presence of a collective blocking process (T B = 165 K) in the system. The dynamical properties studied by χ ac (T) measure- 

ments suggest the existence of a spin-glass phase for T < T S ( = 116.5 K) associated with the magnetic frustration of spins 

in nanocrystal. The presence of glassy magnetic state is supported by the H 2/3 dependence of T S in the intermediate-field 

region (50 ≤ H ≤ 1000 Oe). This behavior is consistent with the de Almeida-Thouless evolution of the energy barriers 

( δT S ~ H 2/3 ) for canonical-spin-glass systems.The frequency (f m ) dependence of χ ac (T) curves reveal that T B and T S essenti- 

ally follow the Vogel–Fulcher law T P = T 0 + T a /ln(f 0 /f m ), in which the attempt frequency (f 0 ) and the activation temperature 

(T a ) are determined for both T B and T S . Various measurement protocols including temperature quenching, step field and 

wait-time dependence have been used to investigate the memory and aging effects in M ZFC for T < T S . The magnetic viscosity 

(S) and microscopic spin-flip time (τ) are deduced from the time dependence of M ZFC using the expression M(t,T) = M(0,T) 

+ S ln(1+t/t 0 ). The role of interparticle interactions on the magnetic relaxation process is discussed. 

subhasht@iitg.ac.in 

35


36 


Spin wave dispersion in a permalloy ring structure using finite element micromagnetic 

simulations 

Guru Venkat 1 , Dasari Venkateswarlu 2 , Rajeev S. Joshi 2 , Hans Fangohr 3 , P.S. Anil Kumar 2 , Anil Prabhakar 1 

1 Indian Institute of Technology Madras, 600036 Chennai, India 

2 Indian Institute of Science Bangalore, 560012 Bangalore, India 

3 University of Southampton, Department of Engineering and the Environment, SO17 1BJ Southampton, UK 

Spin wave (SW) dynamics, in the GHz regime, have been studied, in ring structures, using experiments and finite 

difference micromagnetic simulations [1, 2]. It is better to use the finite element method for analyzing such curved 

geometries. We use a finite element solver, Nmag [3], to investigate SW propagation and dispersion, ω(k), till 200 

GHz, in a ring with two stubs. We observe the effects of different bias fields on ω(k) and quantify the interference 

effects between SWs in the two arms of the ring. 

A permalloy ring of width 100 nm, with inner and outer radii of 500 nm and 600 nm respectively, is attached to 400 

nm long stubs, in an interferometer configuration. The structure had a uniform thickness of 5 nm. A bias field (H ) of 0 

10 kOe ensured that the magnetization was relaxed. Then a sinc excitation pulse, of peak amplitude 5 kOe and cut 

off frequency 200 GHz, was applied. ω(k) of the resulting SWs was obtained along a line in the right stub and along 

a circular arc in the ring. 

In the first simulation, H was applied along the stub length, thereby exciting only backward volume (BV) SWs in the 

0 

stubs but a combination of BV and surface waves in the ring. By introducing regions of high damping at the ends of 

the stubs, we reduced the reflections of SWs and were able to excite propagating modes up to 200 GHz. In a second 

simulation, we were able to remove the effects of interfering BV and surface SWs, by applying H along the circum- 

0 

ference of the ring, so that the ground state is the “onion” state. This led to only BVSWs propagating throughout the 

structure, with a significant improvement in the SW ampitudes. In another simulation, we applied H in the form of 

0 

the “vortex” state in the ring. This led to the symmetry breaking of the magnetization in the two arms of the ring and 

preferrential flow of SWs occured in one of the arms. Thus, based on the configuration of H , we were able to control 

0 

the channelizing of SWs in the arms of the ring. Finally, we assumed current in a Cu underlayer that biased the permalloy 

along the width, in a surface wave configuration throughout the structure to obtain ω (k). 

References 

[1] I. Neudecker et al., Phys. Rev. Lett. 96, 057207 (2006). 

[2] H. Schultheiss et al., Phys. Rev. Lett. 100, 047204 (2008). 

[3] T. Fischbacher et al., IEEE Trans. Magn. 43, 2896 (2007). 

guruvenkat7@gmail.com


Interlayer coupling in NiFe/CoFe/Cu/CoFe/MnIr spin-valves studied by ferromagnetic 

resonance 

Yuriy Pogorelov 1 , Andrey Timopheev 2 , Nikolai Sobolev 2 , Sergey Bunyaev 1 , Susana Cardoso 1 , Paulo Freitas 1 , 

Gleb N. Kakazei 1 

1 IFIMUP-IN, Institute of Nanoscience and Nanotechnologies, University of Porto, 4169-007 Porto, Portugal 

2 University of Aveiro, 3810-193 Aveiro, Portugal 

In-plane angular dependencies of ferromagnetic resonance (FMR) in ion-beam deposited Glass/Ta/NiFe/CoFe/Cu/CoFe/MnIr/ 

Ta spin-valves (SV’s) with Cu-spacer thickness (t ) varying from 14 to 28A were measured.Additionally, samples containing 

Cu 

only free and pinned layers from these SV’s were prepared as a reference. Typical FMR spectra of SV’s reveal two signals 

associated with free and pinned layers (by comparison with the reference samples).The analysis of the FMR data has shown 

that the samples can be classified with respect to the coupling strength between the pinned and free layers into: i) those 

with the strong coupling regime (t = 14, 15 A) where the resonance modes by the two layers are undistiguishable and 

Cu 

the FMR line is noticeably wider than those for the reference samples, ii) those with the weak coupling regime (t > 16 A) 

Cu 

where FMR shows two clearly separated resonance lines due to free and pinned layers with close parameters to those by 

the reference layers, and iii) those with intermediate coupling regime observed in SV with t = 16 A. Besides these FMR 

Cu 

lines, the r.f. absorption by the pinned CoFe layer exhibits a peculiar step when the magnetic field unpins this layer from 

MnIr. This field value, the exchange bias field (H ), monotonically increases from 140 to 280 Oe with t growing from 14 to 

ex Cu 

28 A, indicating a monotonic (non-oscillatory) decay of interlayer coupling.The strongest variation (from 140 to 250 Oe) of 

H ex occurs in the t Cu range from 14 to 17 A, turning weak and practically linear for t Cu > 16 A. Thus, it has been 

concluded that the principal coupling mechanism is the Néel “orange-peel” magnetostatic coupling, supplemented by 

the direct exchange due to pinholes in the Cu spacer for t Cu < 17 A (the density of pinholes decreases with increasing t Cu 

and apparently vanishes at that thickness value). 

ypogorel@fc.up.pt 

37


38 


Interaction between propagating spin-waves and domain walls on a ferromagnetic 

nanowire 

Kim June-Seo 1 , Mathias Kläui 1 , Martin Stärk 2 , M.S. Jungbum Yoon 3 , Chun-Yeol You 3 , Luis Lopez-Diaz 4 , 

Eduardo Martinez 4 

1 Universität Mainz, Institut für Physik, 55128 Mainz, Germany 

2 Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany 

3 Department of Physics, Inha University, 402-751 Incheon, Korea 

4 Department of Physics, Universidad de Salamanca, 37008 Salamanca, Spain 

The recent discovery that propagating spin-waves (SWs) are able to move a domain wall has highlighted a new 

possibility to manipulate magnetization [1,2]. Here, we numerically investigate the interaction between propagating 

SWs and a transverse domain wall in a nanowire by means of micromagnetic simulations. In order to understand 

the mechanisms that lead to domain wall motion, we calculate the domain wall velocities and the depinning fields 

for a pinned domain wall that is depinned in and against the direction of the SW propagation. We highlight that the 

physical origin of the SW induced domain wall motion strongly depends on the propagating SW frequency. At certain 

spin wave frequencies, transverse domain wall oscillations lead to transverse wall displacement by the SWs, while at 

other frequencies, large reflection of SWs and effective momentum transfer are the main drivers of the SW induced 

domain wall motion. 

References 

[1] Dong-Soo Han, et. al., Appl. Phys. Lett. 94, 112502 (2009). 

[2] Madhi Jamali, et. al., Appl. Phys. Lett. 96, 242501 (2010). 

kimj@uni-mainz.de

Plenary Lecture B01-P 

Magnetostatic wave frequency selective limiters 

Douglas J. Adam 

21108 Millersville, USA 

Frequency selective limiters (FSLs), which selectively attenuate above threshold signals while allowing low power signals 

to pass with little attenuation, have potential application in maintaining the dynamic range of RF receivers in the presence 

of interference. Stripline FSLs, fabricated using thick YIG films, are suitable for broadband, microwave applications but have 

typical threshold power levels of 0 dBm which is too high for many RF applications. Here magnetostatic wave (MSW) FSLs 

are described with frequency selectivity and threshold power levels 100 times lower than achieved with stripline devices.The 

performance of an MSW FSL operating in the UHF band will be presented and compared with models for threshold power, 

frequency selectivity and intermodulation products. Based on these results the performance limits of FSLs will be discussed 

with emphasis on reducing threshold power levels significantly below -40 dBm as required in potential GPS applications. 

jd.adam@verizon.net 

39


40 

RF, Microwave and Millimeter Wave devices B02-I 


Magnonic logic architectures driven by microwaves 

Yat-Yin Au, Ehsan Ahmad, Mykola Dvornik, Oleksandr Dmytriiev, Toby Davison, Volodymyr Kruglyak 

University of Exeter, EX4 4QL Exeter, United Kingdom 

The short wavelength of spin waves propagating in nanoscale magnonic waveguides at microwave frequencies could 

potentially provide a device miniaturization opportunity via accomplishing certain tasks in a more efficient manner as 

compared to semiconductor circuitry. However, to utilize this promise of magnonics, one of the important challenges 

is to learn to manipulate the spin wave oscillation phase and magnitude, with this manipulation itself being highly 

related to data encoding and logical operation. Historically, various spin wave phase shifting mechanisms have been 

proposed, including the use of domain walls, local electrical voltage and flow of electrical current, each however 

presenting certain technical limitations. In this report, we will report on the use of the Time Resolved Scanning Kerr 

Microscopy to demonstrate conversion of a global spatially uniform microwave field into spin waves propagating inside 

a waveguide by a reservoir continuous film [1] and a nanomagnet element sitting above a magnonic waveguide 

[2]. Further micromagnetic simulations have demonstrated that the reverse mechanism of the latter version of spin 

wave emission can actually be utilized to provide controllable spin wave absorption or phase shifting [3]. Combined, 

these findings suggest an opportunity of creation of magnonic logic architectures driven by microwaves. The research 

leading to these results has received funding from the EC‘s Seventh Framework Programme (FP7/2007-2013) under 

GAs 233552 (DYNAMAG) and 228673 (MAGNONICS) and from the EPSRC of the UK (EP/E055087/1). 

References 

[1] Y. Au, T. Davison, E. Ahmad, P. S. Keatley, R. J. Hicken, and V. V. Kruglyak, Appl. Phys. Lett. 98, 122506 (2011). 

[2] Y. Au, E. Ahmad, O. Dmytriiev, M. Dvornik, T. Davison, and V. V. Kruglyak, Appl. Phys. Lett. 100, 182404 (2012). 

[3] Y. Au, M. Dvornik, O. Dmytriiev, and V. V. Kruglyak, Appl. Phys. Lett. 100, 172408 (2012). 

V.V.Kruglyak@exeter.ac.uk

RF, Microwave and Millimeter Wave devices B03-I 


Self-biased microstripline ferrite circulators 

Zhijuan Su 1 , Alexander Sokolov 1 , Jianwei Wang 1 , Yajie Chen 1 , Anton Geiler 2 , Lee Burns 2 , Andrew Daigle 2 , 

Carmine Vittoria 1 , Vincent Harris 1 

1 Northeastern University, Boston, MA 02115, USA 

2 Metamagnetics Inc., Canton, MA 02021, USA 

This paper presents novel work on hexaferrite materials and their role in microstripline Y-type circulators that have been 

designed to operate at frequency bands from Ku-Ka. Individual circulators have been optimized via finite element simulation 

software to be compact, utilize unique ferrite properties, and require no bias fields. Self-biased circulators were designed, 

fabricated and tested at Ku, K, Ka bands utilizing strontium M-type barium ferrite.The junction circuit consisted of a dielectric 

slab resting upon a polished thin plate of bulk strontium M-type hexaferrite.This approach proved to be mechanically rigid 

and compatible with the fabrication of integrated circuits yielding practical electrical characteristics of a circulator circuit. As 

an example, the Ku circulator was measured isolation was > 20 dB, and the insertion loss was ~ 1.5 dB at 13.6 GHz. Recent 

work on W-type hexaferrites and self-biased circulators operating at X-band will also be discussed. 

harris@ece.neu.edu 

41


42 

RF, Microwave and Millimeter Wave devices B04-c 

A microwave nonlinear phase shifter based on forward volume spin waves 

Alexey Ustinov 1 , Erkki Lahderanta 2 

1 St.Petersburg Electrotechnical University, 197376 St.Petersburg, Russia 

2 Lappeentanta University of Technology, 53851 Lappeenranta, Finland 

During the past decade nonlinear magnetic oscillations and waves in ferrite films have been attracting a noticeable 

research interest [1,2]. In particular, it has been demonstrated that a nonlinear phase shift of spin waves could be 

used for development of such microwave devices as nonlinear phase shifters [3], nonlinear interferometers [4], and 

nonlinear directional couplers [5]. Purpose of the present work is to study the nonlinear phase shift of spin waves in 

a broad microwave frequency range covering frequencies of such wireless networks as GSM, Bluetooth, Wi-Fi, and 

other. Experiments were carried out with experimental prototype of ferrite-film nonlinear phase shifter similar to 

that described in [3]. The prototype utilized 5.2-µm-thick, 2-mm-wide, and 40-mm-long yttrium iron garnet (YIG) film 

waveguide. The film was epitaxially grown on 500-µm-thick gadolinium gallium garnet substrate. The spin waves in 

the YIG film waveguide were excited and detected by microstrip transducers separated by a 4.6 mm distance.The bias 

magnetic field in the range of H = 1800-5700 Oe was applied perpendicular to the YIG film plane. This corresponds 

the carrier spin wave frequencies in the range of 500-11000 MHz. Experimental dependences of the differential 

nonlinear phase shift Δφ from the input power Pin were measured for different frequencies of the input signal. The 

NL 

results show that an increase in magnetic field lead to reduce in the nonlinear phase shift. Thus, for P = 8 dBm the 

in 

nonlinear phase shift was Δφ ≈ 450 degree for H = 1860 Oe which correspond to frequencies around 600 MHz; 

NL 

Δφ ≈ 330 degree for H =1970 Oe which correspond to frequencies around 900 MHz; and Δφ ≈ 180 degree for 

NL NL 

H = 2485 Oe which correspond to frequencies around 2400 MHz. The obtained Δφ values ensure the potential 

NL 

application of the investigated phenomenon in wireless telecommunication systems. 

References 

[1] Y.S. Gui et al., Phys. Rev. B 80, 184422 (2009). 

[2] U.-H. Hansen et al., Appl. Phys. Lett. 94, 252502 (2009). 

[3] A.B. Ustinov et al., Appl. Phys. Lett. 93, 102504 (2008). 



ustinov_rus@yahoo.com

Magnetization dynamics and Relaxation B05-I 


Effect of spin pumping and domain wall induced coupling on configurational 

dependence of magnetization dynamics in spin valves 

Ruslan Salikhov 1 , Radu Abrudan 1 , Frank Brüssing 1 , Florin Radu 2 , Kurt Westerholt 1 , Ilgiz Garifullin 3 , Hartmut Zabel 1 

1 Ruhr-Universität Bochum, 44780 Bochum, Germany 

2 Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489 Berlin, Germany 

3 Zavoisky Physical-Technical Institute, Kazan Scientific Center Russial Academy of Sciences, 20029 Kazan, Russia 

Spin current related phenomena in F /N/F structures, where F is the ferromagnetic layer and N is the nonmagnetic metal 

1 2 

layer are an important aspect of modern magnetism and can be of use in many different practical applications like charge 

free memory and spin wave electronics. Understanding of spin polarized current phenomena like spin pumping effect [1] 

treats new theoretical predictions which need experimental conformation. For example, J.-V. Kim and C. Chappert [2] theoretically 

investigated the dynamical coupling between magnetic moments of ferromagnetic layers by the spin pumping effect 

in F /N/F structures and concluded that this coupling can lead to configurational dependence of magnetic relaxations. That 

1 2 

can give a unique possibility to control the relaxation rate of F layer by adjusting the magnetization directions of F and F 2 1 2 

layers to be parallel (P) or antiparallel (AP). 

We have studied Co/Cu/Py (where Py = Ni Fe ) spin valve systems with different thicknesses of Cu-spacer layers (25 and 

81 19 

40 nm) using the Time-Resolved X-ray Resonant Magnetic Scattering (TR-XRMS) at the synchrotron radiation facility BESSY 

II of the Helmholtz Zentrum Berlin. This method enables the detection of the free precessional decay of the magnetization 

of ferromagnetic films in response to a field pulse excitation [3].We have found that the magnetic precessional decay time 

of Fe magnetic moments in Py layers decreases when changing the mutual orientation of the magnetization direction of Py 

and Co layers from P to AP, whereas the magnetization precessional frequency does not change. The damping parameters 

are essentially identical for both samples with different Cu spacer layer thicknesses. Taking into account all possible mechanisms 

which can cause the observed effect in our samples, we suppose that the increase of damping for AP orientation 

of magnetizations is associated with the spin-pumping-induced damping effect [4] as it was predicted theoretically in [2]. 

TR-XRMS measurements of another spin valve like system Co MnGe/V/Py reveal that the domain wall (DW) induced coup- 

2 

ling mechanism can also cause the increase in magnetization precession damping parameter in Py layer when changing the 

mutual orientation of magnetizations in ferromagnetic layers from P to AP configuration. Origin of this mechanism is the 

magnetostatic coupling of the ferromagnetic thin layers at interfaces via DW stray fields [5]. 

We show from an experimental point of view that different contributions to the precessional damping in spin valves of the type 

F /N/F can be distinguished by analyzing the precessional frequency for P and AP configurations of the ferromagnetic layers. 

1 2 

References 

[1] Y.Tserkovnyak, et al., Rev. Mod. Phys. 77, 1375 (2005). 

[2] J.-V. Kim, C. Chappert, JMMM 286, 56 (2005). 

[3] St. Buschhorn, et al., J. Phys. D 44, 165001 (2011). 

[4] R. Salikhov, et al.,Appl. Phys. Lett. 99, 092509 (2011). 

[5] L.Thomas, et al., Phys. Rev. Lett 84, 1816 (2000). 

ruslan_salikhov@yahoo.com 

43


44 

Magnetization dynamics and Relaxation B06-c 

Anomalous Hall effect of magnons in inhomogeneous ferromagnetic media 

Sergey Platonov, Ivan Lisenkov, Sergei A. Nikitov 

Kotel‘nikov IRE RAS, 125009 Moscow, Russia 

Spintronics is becoming an area of active research nowadays because of the tremendous potential ahead both in 

terms of fundamental physics and technology. In particular transport of magnons (spin waves) is highly important, as 

the most suitable candidate for the role of the spin information carrier in ferromagnetic structures [1]. Precise control 

over the magnon transport is major task for the applications in spintronics devices. 

In this paper we discover topological magnon transport in periodic magnetic structures (magnonic crystals) [2]. Due 

to analogy drawn to the topological transport of photons [3] or phonons [4], theory of magnon transport is built 

under the Hamiltonian approach. By diagonalizing the magnon kinetic energy in the hamiltonian, we derive the 

gauge potential in the momentum space. The origin of such potential in case of absence of spin-orbital interaction is 

demagnetizing energy. This leads to the appearance of the Berry phase and to an additional anomalous velocity term 

in the equations of motion consequently causing anomalous Hall effect (the presence of a transverse flow of magnons 

in ferromagnetic samples in the case of magnetostatic wave propagation). 

We consider forward volume magnetostatic wave propagation in one and two-dimensional structures. In one-dimensional 

case, each element of the magnonic crystal is a rectangular plate, in two-dimensional case magnonic crystal 

consist of cylindrical rods placed in periodic lattice. Dispersion of spin-wave propagation is computed in magnetostatic 

approximation with transfer matrix method for 1D case and multiple scattering theory for 2D case. Semiclassical 

equations of motion of magnon wavepacket are obtained; trajectories of the wave packet in two-dimensional and 

one-dimensional periodic structures (magnonic crystals ) were calculated. 

The results obtained indicate the presence of magnons cross-current propagating in a bounded sample. The dependence 

of effective Lorentz force for magnon is proportional to Berry curvature, magnon cross-current is significantly 

increased near Gamma point and almost vanished at the edge of Brillouin zone. 

References 

[1] H. Kurebayashi et al., Nat. Mat. 10, 660 (2011). 

[2] S. A. Nikitov, Ph. Tailhades, C. S. Tsai, J. Magn. Magn. Mater. 236, 320 (2001). 

[3] K. Yu. Bliokh and V. D. Freilikher, Phys. Rev. B 72, 035108 (2005). 

[4] K.Yu. Bliokh and V.D. Freilikher, Phys.Rev.B 74, 174302 (2006). 

platonov.serge@gmail.com


Broadband ferromagnetic resonance study of CO 2 MnSi thin films: effect of the film 

thickness 

Guillermo Ortiz 1 , Alberto Garcia 2 , Jamal Ben Youssef 3 , Biziere Nicolas 1 , Fabrice Boust 4 , Jean Francois Bobo 1 , 

Etienne Snoeck 1 , Nicolas Vukadinovic 5 

1 CNRS/CEMES - ONERA, 3100 Toulouse, France 

2 Departamento de Física, IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Universidade do Porto, 

4169-007 Porto, Portugal 

3 Laboratoire de Magnétisme de Bretagne, Université de Bretagne Occidentale, 29285 Brest, France 

4 ONERA, 91123 Palaiseau, France 

5 Dassault Aviation, 92552 Saint-Cloud, France 

Co-based Full Heusler alloys are ternary compounds with the general formula Co 2 YZ, where Y are transition metals and Z 

is a main group element.They are particularly interesting for spintronic applications because of their predicted half-metallic 

behaviour, which ensures a high spin polarization. Besides, this kind of alloys usually shows a low magnetic damping, ideal 

for low loss microwaves applications [1]. 

In this work, the thickness dependence of the static and dynamic properties of Co MnSi (CMS) [2] full Heusler was investiga- 

2 

ted. Five samples with thickness ranging from 7 nm to 100 nm were deposited by rf magnetron sputtering on single crystal 

MgO(001). X ray diffraction and Transmission Electron Microscopy (TEM) evidence the epitaxial growth of samples, with an 

epitaxial relationship MgO[100]//CMS[110]. 

Static magnetic measurements (MOKE andVSM) show that thicker samples have a saturation magnetization M value close 

s 

to the theoretical value of 1.257 T. Moreover, the samples exhibit an in-plane fourfold anisotropy. 

Magnetic dynamics was studied by broadband microstrip FMR within a large frequency range (3 – 40 GHz) and for various 

orientations of the polarizing magnetic field with respect to the sample’s plane (out-of-plane and in-plane configurations). 

These measurements enable determination of the gyromagnetic factor γ, the cubic anisotropy constant K and an effective 

c 

magnetization M . As a function of thickness, γ remains almost constant. In contrast, the amplitude of K and 4πM eff c eff 

increases for decreasing thicknesses. This last evolution will be discussed in terms of surface anisotropy. In addition, evolution 

of resonance fields with frequency and orientation for Perpendicular Standing Spin Waves (PSSW) observed for thicker 

samples allowed to estimate the exchange constant A = 1.74×10 -11 (J/m). 

Magnetic damping was then studied using the in-plane frequency measurements along the easy and the hard axis as well 

as rotation measurements. An anisotropic damping parameter is revealed except for the thinnest sample. The lowest value 

of the damping parameter is a = 2 × 10-3 in agreement with the previously published values [3]. 

References 

[1] Trudel et al., J. Phys. D:Appl. Phys. 43 193001 (2010). 

[2] Hamrle et al., J.Appl. Phys. 103, 103910 (2008). 

[3] Yilgin et al., J.Appl. Phys. 46, L205 (2007). 

guillermo.ortiz@cemes.fr 

45


46 


Spin wave properties of two-dimensional magnetic superlattices 

Glade Sietsema, Michael Flatté 

University of Iowa, 52246 Iowa City, USA 

We have studied the behavior of spin waves in two-dimensional periodic magnetic superlattices. These magnonic 

crystals consist of magnetic cylinders arranged in either a square or hexagonal lattice and embedded within a second 

magnetic material. Spin wave frequencies and linewidths are calculated from the Landau-Lifshitz-Gilbert equations. 

Dramatic changes in the magnonic spectrum are shown to occur when varying the saturation magnetization and 

exchange stiffness constants of the two materials. For example, multiple band gaps across the entire superlattice Brillouin 

zone appear when the saturation magnetization of the cylinders is much larger than that of the magnetic host. 

Additionally, we use Green‘s function calculations to examine the superlattice‘s response to pulse excitations, such 

as from a spin torque oscillator.The directional dependencies of these excitations is shown to vary with the frequency 

of the pulse. This work is supported by an ARO MURI. 

glade-sietsema@uiowa.edu

high Frequency Materials B09-I 


Spin-wave dynamics in lateral periodic and quasiperiodic magnetic micro- and 

nanostructures – magnonic crystals 

Sergei A. Nikitov 1 , Yury Filimonov 1 , Yuri V. Khivintsev 1 , Evgenii Pavlov 2 , Valentin Sakharov 2 , Sergey Vysotsky 2 

1 Kotel‘nikov IRE RAS, 125009 Moscow, Russia 

2 410009 Saratov, Russia 

Magnetic periodically structured ferromagnetic films being a microwave analog of photonic and phononic crystals have 

created a revival interest of spin waves (SW) investigations in periodically micro- and nanostructured magnetic media, which 

are called magnonic crystals (MC). However SW propagation in such structures has some specific properties untypical for 

both optic and elastic waves. Namely, they possess strong nonlinearity, anisotropic and nonreciprical propagation characteristics 

even for the case of wave propagation in isotropic materials. Besides that, ferromagnetic films being a base for MC 

with strong magnetostriction due to resonance interaction between excitations of magnetic and elastic subsystems lead to 

a new unusual effects. Such peculiarities of SW propagation in MC are interesting and important both from fundamental 

and practical points of view as they can be important for microwave signal processing on the basis of magnonic crystals. In 

this paper we review the recent results of propagating and localized spin-waves excitations in magnetic thin film structures 

with micro- or nanosize features arranged in lateral one- (1D) or two-dimension (2D) periodic arrays. Such fundamental 

phenomena as anisotropic Bragg scattering and quantization of SW are discussed as well opportunities to control the 

magnonic crystals parameters due to metal screening and nonlinearity of magnetic system. Some attention will be paid to 

magnetoelastic interaction in epitaxial yttrium iron garnet/gadolinium iron garnet (YIG/GGG) structures with microstructured 

surface of ferromagnetic YIG film. We also review results of ferromagnetic resonance (FMR) investigations of localized 

SW modes in MC crystals based on metallic ferromagnetic films: permalloy (Py) films sputtered on patterned nonmagnetic 

substrate, bicomponent (Py and Co) MC and antidote lattices. 

nikitov@cplire.ru 

47


48 

high Frequency Materials B10-I 


Soft Magnetic Thin Film Application to Suppress Electromagnetic Noise On LTE-Class RFIC 

Masahiro Yamaguchi 1,2 , Yasushi Endo 1 , Sho Muroga 1 , Makoto Nagata 3 , Satoshi Tanaka 4 

1 Department of Electrical Engineering, Tohoku University, 980-8579 Sendai, Japan 

2 New Industry Creation Hachery Center(NICHe), Tohoku University, 980-8579 Sendai, Japan 

3 Graduate School of System Informatics, Kobe University, 657-8501 Kobe, Japan 

4 Mobile Multimedia Business Unit, Renesas Mobile Corporation, 370-0021 Takasaki, Japan 

Development of new passive component technologies will enable a “More-than-Moore” paradigm leading to inno- 

vative application-specific compact systems [1]. Ferromagnetic thin film materials, having high permeability at (and 

above) radio frequencies, are candidate materials for use in inductive passive components. Using these materials, the 

development of CMOS integrated inductors and integrated electromagnetic noise suppressors for Long Term Evolu- 

tion, or 3.9th Generation, cell phone RFIC and Point-of-Load one-chip DC-DC converters, is attracting great interest 

from both academic and industrial communities. 

This talk begins with a review of new soft magnetic thin film applications at radio frequencies for future systemin-package 

(SiP) and system-on-chip (SoC) technologies, and then focuses on small signal lossy application of the 

films to CMOS integrated electromagnetic noise suppressor [2]. The outline of the problem is to analyze and countermeasure 

the intra-chip digital-to-analogue noise attack; i.e. The harmonics of digital clocks conflict with certain 

sub-channels in the receiver frequency band, which causes the user-noticeable desensitization of the RF receiver. So 

far as the noise is associated with electric currents, the FMR losses in magnetic film could be used as a frequencyselective 

noise suppressor. 

The TEG chip consists of low noise amplifiers (LNA), mixer, voltage controlled oscillator, gain programmable amplifier, 

and low pass filter, which are implemented in CMOS 65nm technology[3].Arbitrary noise generator(ANG) and on-chip 

substrate voltage monitors(OCM) are also implemented. The TEG chip receives the analogue LTE signal, and outputs 

analogue I/Q signal. Details of the circuit design and performance will be published elsewhere. 

RF magnetic shielding effectiveness of Co Zr Nb thin-film was integrated onto the surface of the TEG chip by 

85 3 12 

RF sputtering. The CoZrNb film is with Ms=1.0T, Hk=1.0 kA/m, electric resistivity ρ=1.2×10-8Ωm, FMR frequency 

f =1.2GHz. The magnetic near field image at 2158MHz (in the LTE Band 1; 2110-2170MHz for downlink) was measu- 

r 

red by a planar shielded-loop type magnetic field probe[3] having 60x60 µm2 coil we newly developed for this particular 

measurement[4]. It was clarified that the radiated emission on the ANG by 5dB, and that on the RF analogue 

circuits by 15dB at most. Degree of suppression differs due to the different mechanisms. 

This work is supported in part by the Radio Use, MIC, Japan. 

[1] John P. Kent, and Jagdish Prasad, IEEE 2008 CICC, 15-4-1 (2008). 

[2] Sho Muroga, et al, IEEE Trans. Magn. 48, 4485(2011). 

[3] S. Tanaka, IC chip level low noise technology workshop, CEWS-1-5, (2011, in Japanese) 

[4] S. Muroga et al, submitted to Joint MMM/Intermag 2013 conference.

high Frequency Materials B11-c 

Enhanced microwave permeability and Mössbauer spectra of Fe-Si-Al flakes 

Mangui Han 1 , Konstantin Rozanov 2 , JunFeng Qin 1 , Longjiang Deng 3 

1 State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology 

of China, 610054 Chengdu, China 

2 Institute for Theoretical and Applied Electromagnetics, Russian Academy of Sciences, 125412 Moscow, Russia 

3 University of Electronic Science and Technology of China, 610054 Chengdu, China 

Recently, there is an increasing interest in Fe-Si-Al alloys due to their promising applications in suppressing the unwanted 

electromagnetic radiations from electronic devices working in the microwave band [1]. In this contribution, we have studied 

the microwave permeability of Fe-Si-Al alloys and employed the Mössbauer spectroscopy to uncover the physics for the 

enhanced permeability.The microwave permeability of milled Fe-Si-Al flaky particles has been found much larger than those 

of unmilled particles with irregular shape.The volume fraction dependence of microwave permeability of Fe-Si-Al composi- 

tes have been studied. Based on the Landau−Lifshitz−Loyenga mixing rule, the intrinsic microwave permeability have been 

extracted for the flaky Fe-Si-Al particles.The results showed that the microwave magnetic loss is strong, which is beneficial 

for microwave absorption. The efficient dynamic magnetization has been found according to the generalized Snoek’s law 

proposed by Acher et al [2]. Besides, Mössbauer spectra are found significantly different for particles with different shapes. 

More than 8 absorption peaks have been found for the unmilled particles. While there are only 6 absorption peaks for 

the flaky particles. The unmilled particles are found with the ordered D03 type superlattice structure, and therefore can 

be fitted with 5 sextets representing 5 different Fe-site environments. However, the flaky particles are with disorder 

a-Fe(Si, Al) structure, and can be fitted with the distribution of hyperfine magnetic field and isomer shift. It also has been 

revealed by Mössbauer spectra that the flaky particles have stronger tendency to possess the planar magnetic anisotropy, 

and their average magnetic moment is found to be about 1.63 µ B . 

References 

[1] L. Liu, Z. H.Yang, C. R. Deng, Z.W. Li, M.A.Abshinova, and L. B. Kong, J. Magn. Magn. Mater. 324, 1786 (2012). 

[2] O.Acher and S. Dubourg, Phys. Rev. B 77, 104440 (2008). 

mangui@gmail.com 

49


50 


Two-dimensional magnonic crystal with periodic thickness variation in YIG layer for 

magnetostatic volume wave propagation 

Kai-Hung Chi, Yun Zhu, Chen Tsai 

University of California, 92697 Irvine, USA 

The potential of miniaturized structures to control and process RF signals using magnonic crystals (MCs) has long 

been recognized. A number of theoretical approaches for studying the propagation characteristics of magnetostatic 

waves (MSWs) in MCs of distinct periodic structures, e.g. periodic holes or periodic arrangement of material parameters, 

have been reported. To the best of our knowledge, the relationship between bandgaps and thickness variation 

in two-dimensional (2-D) MCs with periodic variation in layer thickness, e.g. etched holes, has not been studied 

heretofore. Note that the structures with thickness variation will facilitate an additional design parameter and thus 

versatility. Here we propose an approach for this purpose with magnetostatic volume waves (MSVWs) by extending 

the one derived from Walker’s equation [1-2] to study the propagation characteristics of MSVWs in such 2-D MCs. 

The approach has been validated by HFSS simulation with excellent agreements. The complete band structures of 

two periodic structures in YIG layer, square lattice and hexagonal lattice as studied in [3], have been calculated 

and analyzed. Larger bandgaps are found in the hexagonal lattice with lattice constant a = 100 µm, filling factor of 

0.23 for the etched portion, and layer thicknesses of 100 and 50 µm of non-etched and etched portion, respectively. 

The relationship between bandgap and layer thickness ratio is delineated readily to provide the optimal design of 

2-D MCs. In general, the frequency range of a bandgap increases and then decreases as the thickness ratio increases. 

The related experiments are in progress, and the results will also be reported. Supported by UC Discovery Program 

and Shih-Lin Electric Corp., USA. 

References 

[1] K. H. Chi, Y. Zhu, R. W. Mao, J. P. Dolas, and C. S. Tsai, J. Appl. Phys., 109, 07D320 (2011). 

[2] K. H. Chi, Y. Zhu, R. Mao, S. A. Nikitov, Y. V. Gulyaev, and C. S. Tsai, IEEE Trans. Mag., 47, 3708-3711 (2011). 

[3] S. A. Nikitov, C. S. Tsai, Y. V. Gulyaev, Y. A. Filimonov, A. I. Volkov, S. L. Vysotskii, and P. Tailhades, 

Mater. Res. Soc. Symp. Proc., 384, J 2.2.1 (2005). 

cstsai@uci.edu


Magnetic nanometal coated polyacrynitrile textiles as microwave absorber 

Huseyin Kavas 

Gebze Institute of Technology / Physics, 41400 Kocaeli,Turkey 

The polyacrylonitrile (PAN) textiles with 2 mm thickness are coated with magnetic nano metals in coating baths with Ni, 

Co and their alloys via the electroless metal deposition method. The crystal structure, morphology and magnetic nature 

of composites are investigated by XRD, SEM and usual dc magnetization measurement techniques, respectively. The mic- 

rowave absorption measurements have been carried out as a function of frequency between 12.4 GHz to 18 GHz (X and P 

Bands). The results show that the coating conditions especially, time, are the most important factor in obtaining composites. 

Moreover, the diamagnetic and ferromagnetic properties are investigated together. Finally, the microwave absorption 

of composites are found to have been strongly dependent of coating time. One absorption peak is observed between 

14.3-15.8 GHz with a efficient absorption bandwidth of 3.3-4.1 GHz (under -20 dB reflection loss limit).The Reflection loss 

(RL) reached to -30 and -50 dB values. It was found that the RL is decreasing and absorption bandwidth is declining with 

increasing coating time. As coating time increases, absorption peak shifts to lower frequencies in Ni coated PAN textile, 

while it goes higher frequencies in Co coated ones. Finally it has been observed that the RL due to the dielectric loss much 

less than RL due to the magnetic loss in all composites. 

hkavas@gyte.edu.tr 

51


52 


FeCoBSi thin film based magnetic structural materials for microwave applications 

Peiheng Zhou 1 , Huibin Zhang 2 , Haipeng Lu 2 , Jianliang Xie 1 , Longjiang Deng 1 


2 State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and 

Technology of China, Chengdu 610054, China 

Magnetic materials have long been used for microwave electromagnetic applications, such as antenna substrates, 

radar absorbents, tunable filters and so on. FeCo-based magnetic thin film has been considered as a prominent candidate 

due to the ultra-high permeability at microwave frequencies which breaks Snoek’s law. However, two problems 

still exist-high conductivity and ultrathin thickness. The former induces near-unity reflection of the incident wave, 

while the later limits the efficiency of magnetic permeability and predicts a narrowband character by the Rozanov 

limit. 

In this work, two approaches are explored to control the effective permeability and permittivity of the FeCoBSi 

thin film based magnetic structural materials. Our purpose is to improve the electrical performance and utilize the 

magnetic characteristics of the thin film by structural design. 

Patterning in micrometer scale is achieved by lithography technique. Periodical circular holes with various diameters 

and strips with different widths are introduced respectively. It is found that the effective permeability and permittivity 

are adjusted by the insulating phase and interface. The evolution of magnetic domain structure, damping parameter, 

and surface resistance are found to be the main reasons. Multi-resonances are also observed and explained by 

dynamic magnetic theories. 

Rolling the FeCoBSi thin film on a copper wire introduces a unique metamaterial unit. The ultrathin thickness of thin 

film leaves a negligible distance for the incident microwave field experiencing high permeability. However, in the 

proposed unit, the incident magnetic field is concentrated within the thin film to promise a high efficiency of magnetization 

performance as the incident electric field is confined by the copper core. Absorbers utilizing this approach are 

introduced to illustrate the design method and the further application of this kind of structures. 

phzhou@uestc.edu.cn


Microwave permeability behaviour of FeNiMo flakes-polymer composite with 

an applied static field 

Julien Neige 1 , Thomas Lepetit 1 , Nicolas Malléjac 1 , Anne-Lise Adenot-Engelvin 1 , André Thiaville 2 , 

Nicolas Vukadinovic 3 

1 CEA-DAM Le Ripault, 37260 Monts, France 

2 Laboratoire de Physique des Solides, Univ. Paris-Sud, 91405 Orsay, France 


Recently, many investigations have been devoted to microwave properties of magnetic particle composites. These have 

been carried out because electromagnetic interference has become a critical problem due to the widespread application 

of wireless technology [1]. In this work, we used commercially available micrometer-sized FeNiMo flakes with large aspect 

ratio embedded in a polymer matrix, whose planes lie parallel to the composite sheet plane, prepared by long-duration 

microforging [2]. To understand the magnetization dynamics of such a composite, microwave measurements with an 

applied static field were performed in order to vary the magnetization state of the sample. Various volume fractions and 

sizes of the FeNiMo flakes were investigated. 

Composite magnetic sheets were elaborated by tape casting. Measurements of the complex permeability were performed 

by a microstrip line perturbation method using a Rhode&Schwartz vector network analyzer in the frequency range 

1-8 GHz [3].The setup allows measurements in two directions, namely with the static field parallel and perpendicular to the 

microwave field of the coil. 

In the case of samples made of 20% vol FeNiMo flakes, the frequency dependence of the permeability shows 2 peaks. First, 

for an increasing static field below 150 Oe, the first permeability peak increases and moves towards high frequencies (from 

2.5 GHz to 3.5 GHz).Then, between 150 and 200 Oe, we observe an intermediate state between a first and a second peak 

around 4 GHz. Last, above 200 Oe, this second peak first increases (and reaches its maximum at the hysteresis loop closing 

field) and then decreases above 5.8 GHz. For both peaks, the field dependence of resonance frequency is linear but exhibits 

a different rate. 

The static field at which the intermediate state is observed depends on both the volume fraction and size of the flakes. 

However, it always occurs at around 4 GHz. This complex behaviour cannot be explained by a macrospin approach on the 

whole range of field. As a full micromagnetic approach is out of the scope of this study, a qualitative model based on the 

static magnetization changes of the sample is proposed. 

References 

[1] J. Wei et al., J.App. Phys. 108, 123908 (2010). 

[2] S.Yoshida et al., J.App. Phys. 93, 6659 (2003). 

[3] D. Pain et al., J.App. Phys. 85, 5151 (1999). 

julien.neige@cea.fr 

53


54 


Magnetic damping in ferromagnetic nanowire arrays 

David Menard, Louis-Philippe Carignan 

Ecole Polytechnique Montreal, H3T 1J4 Montreal, Canada 

Arrays of metallic ferromagnetic nanowires (FMNWs) offer considerable design flexibility for the engineering of the 

microwave properties of magnetic materials. Usually fabricated by relatively inexpensive electroplating techniques, 

they are also compatible with microwave integrated circuit technologies. However, this increased design flexibility 

and integrability is provided at the cost of higher microwave losses as compared to state-of-the-art ferrites and 

garnets currently used in devices. Understanding and reducing the microwave losses remain probably the biggest 

challenges for these promising materials. 

We studied the frequency and angle-dependent ferromagnetic resonance (FMR) linewidth of a variety of Ni and 

CoFeB FMNW arrays, electroplated into nanoporous alumina membranes. Overall, their static magnetic response - as 

measured by vibrating sample magnetometry (VSM) - and their FMR response are well accounted for by considering 

the systems as two magnetically uniform bistable sub-arrays of nanowires strongly interacting by dipolar interactions. 

A contribution of the effective field which scales with the inverse of the wire diameters also suggest a surface related 

contribution to the magnetic anisotropy. The phenomenological description of the damping in terms of a frequency 

dependent linewidth related to intrinsic mechanisms along with a frequency independent contribution attributed to 

inhomogeneous broadening suggest that the damping is largely dominated by inhomogeneous contributions. This 

inhomogeneous contribution is shown to correlate with the effective anisotropy field and is thus directly related 

to dipolar interactions. It is fair to ask whether these intrinsically non-uniform composite materials are intrinsically 

limited by two-magnon scattering mechanisms usually associated with extrinsic broadening.The experimental results 

will thus be discussed in terms of the relative contributions of different loss mechanisms, highlighting the possible 

the limitations due to two-magnon scattering. The presentation will be concluded with a general assessment of the 

potential of FMNWs for use as a magnetic material for microwave devices. 

david.menard@polymtl.ca

Nonlinear Phenomena B17-I 


Tunable artificial multiferroic structures: Linear and nonlinear microwave properties 

Boris Kalinikos 

St. Petersburg Electrotechnical University, 197376 St. Petersburg, Russia 

One of the modern areas in physics and technology comprises fundamental investigations and engineering applications 

of multiferroic materials. Multiferroic materials can be divided into several classes. One of the classes consists of the 

so-called “natural multiferroics” (see, e.g. [1]). Another class consists of the “artificial materials” that are fabricated by 

a combination of different type of materials, such as ferrite and ferroelectric films (see, e.g. [2]), and field-induced periodical 

variations of the magnetic and/or electric parameters of these materials. It is clear that the combination of ferrite and 

ferroelectric films in a multi-layered structure offers the possibility of simultaneous “magnetic” and “electric” tuning of the 

microwave properties. From our point of view, the artificial multiferroics in a form of multi-layered structures, such as a yttrium 

iron garnet (YIG) and barium strontium titanate (BST) layered heterostructure, demonstrates effects that are currently 

the most interesting for microwave applications (see, e.g. [2] and literature therein). Such effects include electrically tunable 

linear and nonlinear phase shifts, electrically tunable group time delay, electrically tunable frequency filtering, electronically 

controllable formation of stable spin-wave envelope solitons, and chaotical generation of microwave waveforms. Particularly, 

the recent advances in the area contain the use of nonlinear effects in hybrid ferrite-ferroelectric layered materials 

to elaborate nonlinear microwave devices. The aim of this presentation is two-fold: (1) to review briefly the theory and 

physics of linear and nonlinear hybrid “electromagnetic wave” - “spin wave” processes in thin ferrite-ferroelectric layered 

structures as a basis for device applications, and (2) to present two types of device structures, namely, a feedback active 

ring and a nonlinear phase shifter. The main attention will be given to the active ring based on the YIG/BST heterostructure. 

Active ring-based devices will be presented, including the single-mode and multi-mode frequency tunable resonators, 

high Q-factor resonators, matched filters, and stable and chaotic solitonic waveform generators. 

References 

[1] D. Khomskii, Physics 2, 20 (2009). 

[2] Ce-Wen Nan, et al., J.Appl. Phys. 103, 031101 (2008). 

borisk@lamar.colostate.edu 

55


56 

Nonlinear Phenomena B18-I 


Generation of chaotic microwave pulses in ferromagnetic film ring oscillators under 

external influence 

Sergey V. Grishin 1 , Yurii P. Sharaevskii 1 , Sergei A. Nikitov 2 , Dmitrii V. Romanenko 1 

1 Saratov State University, 410012 Saratov, Russia 

2 Kotel‘nikov IRE RAS, 125009 Moscow, Russia 

Nowadays one of the perspective information signals is a chaotic microwave (MW) signal. This signal is presented by 

chaotic microwave pulse trains that are also called chaotic MW pulses [1]. Chaotic MW signals can be generated in 

ring oscillators based on the ferromagnetic films. The parametric or modulation instabilities of magnetostatic waves 

(MSW) in a ferromagnetic film are the cause of a chaos self-generation. Self-generation of chaotic MW pulses was 

observed in the frequency range where three-wave parametric instability of MSW existed [2, 3]. 

In this paper, the experimental results of MW chaotic pulse generation under an external influence are presented. 

As the external influence, three types of MW signals are used: a harmonic MW signal, a pulse-modulated (PM) MW 

signal and a narrowband noise. The suppression of chaotic dynamics of a ring oscillator is observed when the power 

of a harmonic signal corresponds to the input signal power level of a power amplifier at which a saturation regime is 

presented. In the case of PM MW signal, the periodical sequences of chaotic pulses are formed on the time intervals 

where the external MW pulses are absent. The pulse ratio of chaotic MW pulses is inverted to the pulse ratio of external 

MW pulses and the integral power of chaotic MW pulses can be greater than the integral power of a chaotic 

signal in autonomous regime. In the case of the narrowband noise, the solitary chaotic pulse generation is observed. It 

is determined, that a correlation time of solitary chaotic pulses has a maximum at some values of the noise intensity. 

For description of these phenomena, the model of parametric media with amplification is constructed. This model is 

based on the Landau–Lifshitz equation. The model describes transition to chaos in autonomous regime and chaotic 

MW pulse generation in non-autonomous regime. The experimental data are compared with the calculation results. 

This work was supported by the Grant from the President of Russian Federation for Support of Leading Scientific 

Schools (Project No. 1430.2012.2), Government of Russian Federation for support of scientific research in the Russian 

universities under the guidance of leading scientists (Project No. 11.G34.31.0030), the Russian Foundation for Basic 

Research (Project No. 11-02-00057), and the Federal Target Program “Scientific and scientific-educational personnel 

of innovative Russia” (Project No. 14.740.11.1078). 

References 

[1] A. S. Dmitriev and A. I. Panas, Dynamic Chaos: Novel Type of Information Carrier for Communication Systems 

(Fizmatlit, Moscow, 2002). 

[2] M. Wu, B. A. Kalinikos, and C. E. Patton, Phys. Rev. Lett.95, 237202 (2005). 

[3] S.V. Grishin,Yu. P. Sharaevskii, S.A. Nikitov, E. N. Beginin, and S. E. Sheshukova, IEEE Trans. on Magnetics 47, 3716 (2011). 

grishfam@sgu.ru

Nonlinear Phenomena B19-c 

Nonlinear emission of spin-wave caustics from an edge mode of a micro-structured 

Heusler waveguide 

Thomas Sebastian 1 , Philipp Pirro 1 , Thomas Brächer 1 , Alexander Serga 1 , Takahide Kubota 2 , Hiroshi Naganuma 2 , 

Mikihiko Oogane 2 , Yasuo Ando 2 , Burkard Hillebrands 1 

1 Fachbereich Physik and Forschungszentrum OPTIMAS,Technische Universitaet Kaiserslautern, 67663 Kaiserslautern, 

Germany 

2 WPI Advanced Institute for Materials Research, 980-8577 Sendai, Japan 

Cobalt-based full Heusler compounds are very promising candidates for future magnon spintronics devices and the 

observation of novel phenomena in magnonic transport in magnetic microstructures. In comparison with conventional 

metallic 3d-ferromagnets, the Heusler materials show a small magnetic Gilbert damping, a high spin-polarization, and high 

Curie-Temperature.[1] 

As shown recently, the decay length of propagating spin waves in a micro-structured spin-wave waveguide made of the 

Heusler compound Co2Mn 0.6 Fe 0.4Si (CMFS) shows a significant increase in comparison with wave propagation in the com- 

monly used Ni 81 Fe 19 .[2] This observation could be attributed to the decreased Gilbert damping of α = 3×10 -3 in CMFSwith 

respect to the damping constant of α = 8×10 -3 inNi 81 Fe 19 . The decreased magnetic losses not only lead to an increase of the 

decay length but also to large precession angles of the magnetic moments and, thus, to the occurrence of nonlinear effects 

as well.[3] Regarding the use of Heusler materials in future magnon-spintronics devices, it is essential to investigate and to 

understand the spin-wave propagation in the nonlinear regime thoroughly. 

We report nonlinear higher harmonics generation leading to the emission of caustic spin-wave beams from a localized edge 

mode in a low-damping, micro-structured CMFS waveguide.[4,5]The spin waves radiated from this localized source at twice 

and three times the excitation frequency are excited resonantly by nonlinear magnon-magnon interactions. The radiation 

characteristics of these caustic waves are described by an analytical calculation based on the anisotropic dispersion relation 

of spin waves in magnetic thin films.[6] 

References 

[1] S.Trudel, et al., J. Phys. D:Appl. Phys. 43, 193001 (2010). 

[2] T. Sebastian, et al.,Appl. Phys. Lett. 100, 112402 (2012). 

[3] A.G. Gurevich, G.A. Melkov, Magnetization Oscillations and Waves (CRC, Boca Raton, 1996). 

[4] C. Bayer, et al., Phys. Rev. B 69, 1 (2004). 

[5] T. Schneider, et al., Phys. Rev. Lett. 104, 1 (2010). 

[6] B. Kalinikos,A. Slavin, J. Phys. C: Solid State 19, 7013 (1986). 

tomseb@physik.uni-kl.de 

57


58 

Nonlinear Phenomena B20-c 

Nonlinear ferromagnetic resonance in magnetic nanostructures having a discrete 

spectrum of spin wave modes 

Gennady Melkov 1 , Denys Slobodianiuk 1 , Vasyl Tiberkevich 2 , Andrei Slavin 2 

1 Taras Shevchenko National University of Kyiv, 01601 Kyiv, Ukraine 

2 Department of Physics, Oakland University, Rochester, MI 48309, USA 

The classical theory of nonlinear ferromagnetic resonance (FMR) in bulk magnetic samples [1-2] is based on the 

assumption that when the amplitude of the main FMR modes exceeds a certain threshold, this mode becomes 

unstable in respect to parametric excitation of spin wave modes having the frequencies that are either twice smaller 

than the FMR frequency (first-order Suhl processes) or equal to the FMR frequency (second order Suhl processes). 

It is generally considered that the necessary condition for such instabilities is the presence of the FMR frequency or/ 

and its half in the spin wave spectrum of a magnetic sample. The interest to nonlinear spin wave phenomena has been 

recently revived by the discovery of spin-transfer torque [3-4] that can result in excitation of strongly nonlinear spin 

wave modes in magnetic nanostructures [5]. The spin wave spectra of magnetic nano-structures ( and, in particular, 

of magnetic nanopillars) is discrete, and the conservation laws of a standard parametric resonance [1,2] typically can 

not be fulfilled in such structures. In this work we demonstrate that in the case of a nano-object having discrete spin 

wave spectrum the parametric instability process also take place, but are non-resonant, so that the frequencies of 

the parametrically excited spin wave modes are neither equal to the FMR frequency nor to its half, and the power 

thresholds of such non-resonant process are higher than in the traditional case of a continuous spin wave spectrum 

[1,2]. These non-resonant parametric processes are responsible for the energy exchange between the excited spin 

wave modes and for the limiting of the amplitude of the main FMR mode. It is demonstrated that both first- and 

second-order Suhl processes [1] of parametric interaction are possible under non-resonance conditions in magnetic 

nano-structures. The developed theory provides a good qualitative description (both analytical and numerical) 

of the recent experiments where simultaneous excitation of two spin wave modes has been observed by the method 

of magnetic resonance force microscopy in perpendicularly magnetized magnetic nano-pillars driven by bias direct 

current and microwave external signals [6]. 

References 

[1] H. Suhl, J. Phys. Chem. Solids 1, 209 (1957). 

[2] V. S. L’vov, Wave Turbulence Under Parametric Excitation (Springer-Verlag, New York, 1994). 

[3] J. C. Slonczewski, J. Magn. Magn. Mater. 159, L1 (1996). 

[4] L. Berger, Phys. Rev. B 54, 9353 (1996). 

[5] A. Slavin and V. Tiberkevich, Phys. Rev. Lett. 95, 237201 (2005). 

[6] A. Hamadeh et al., Phys. Rev. B 85, 140408R (2012). 

slavin@oakland.edu


Plenary Lecture c01-P 

Autonomous and non-autonomous dynamics of spin-torque oscillators: general theory 

and new developments 

Andrei Slavin, Vasyl Tiberkevich 

Department of Physics, Oakland University, Rochester, MI 48309, USA 

It has been demonstrated in [1] that dynamics of spin-torque nano-oscillators (STNO) can be described by the general 

model of a nonlinear auto-oscillator [1]. It has been also demonstrated in [1] that when the STNO generates at a stable 

limit cycle and the external signal is sufficiently small, the non-autonomous dynamics of the STNO is determined 

by two parameters, that are the dissipation rate of amplitude fluctuations in the STNO and the dimensionless STNO 

nonlinearity coefficient. In our current report we, first of all, show that the dissipation rate of amplitude fluctuations 

in the STNO and the dimensionless STNO nonlinearity coefficient could be determined experimentally from the simple 

frequency-domain measurements of the linewidths of higher harmonics generated by the STNO [2]. We prove 

that the general auto-oscillator formalism [1] can be extended for the case of current-induced gyrotropic motion in 

vortex-state magnetic nano-structures [3] and, using [4] calculate the typical STNO parameters for the gyrotropic 

mode. We also generalize the auto-oscillator formalism [1] and for the case when two (or several) spin wave modes 

are simultaneously excited in the STNO [5, 6]. In the case of the simultaneous two-mode excitation we analyzed the 

Hamiltonian (non-dissipative) dynamics of the STNO and developed a classification of the possible two-mode oscillation 

regimes. We show that the following regimes are possible: (i) single-mode regimes, in which only one of the 

modes is excited; (ii) incoherent two-mode regime, in which both modes are oscillating at independent frequencies; 

(iii) locked two-mode regime, in which frequencies of the two oscillating modes remain the same, either on average 

or exactly. The STNO oscillation regime realized experimentally is chosen by the forms of dissipative functions of the 

interacting oscillation modes. In particular, the incoherent two-mode regime (ii) might result in the mode hopping 

with the hopping frequency equal to the difference of the frequencies of the excited modes. It is likely that this dynamical 

regime was observed in [5]. 

References 

[1] A. Slavin and V. Tiberkevich, IEEE Trans. Magn. 45, 1875 (2009). 

[2] M. Quinsat et al., “Linewidth of higher harmonics in spin torque oscillators”, CD-11, Abstracts of the INTER- 

MAG-2012 Conference, Vancouver, Canada, May 2012. 

[3] V.S. Pribiag et al., Nature Phys. 3, 498 (2007). 

[4] K. Y. Guslienko et al., J.Phys.: Conf. Series 292, 012006 (2012). 

[5] S. Bonetti et al., Phys. Rev.Lett. 105, 217204 (2010). 

[6] A. Hamadeh et al., Phys. Rev. B 85, 140408R (2012). 

slavin@oakland.edu 

59


60 

Spin-torque oscillators c02-I 


Spatial profile of spin waves excited by a spin-torque oscillator and by coplanar 

waveguides 


CNISM, Unità di Perugia and Dipartimento di Fisica, Università di Perugia, 06123 Perugia, Italy 

Brillouin light scattering (BLS) is a well established technique to detect either thermal or externally driven spin waves in thin 

magnetic films. In conventional measurements the spatial resolution is limited to several microns, while using micro-focused 

BLS the probing laser light can be concentrated onto a sub-micrometric spot and two-dimensional maps of the mode intensity 

can be performed, thanks to automatic active stabilization and auto-focusing routines which can compensate sample 

mechanical drift. 

Here we show that this technique has been successfully applied to the detection of SWs injected by an out-of-plane 

magnetized spin torque oscillator (STO) in a free magnetic layer underneath the nano-contact [1]. By a proper control 

of the collecting angle of scattered photons, experimental evidence of the propagating nature of SWs emitted from the 

STO is provided. It is shown that the propagating SW intensity decays several microns away from the nano-contact posi- 

tion, suggesting the possibility of achieving the synchronization of several STOs placed in close proximity to one-another. 

The STO tunability as a function of both the applied direct current and the external field intensity was also investigated 

through detection of the emitted spin waves. 

Recently, the micro-BLS setup was completed with the addition of the phase-contrast option, so that not only the intensity, 

but also the phase of excited spin waves can be detected. Here we present preliminary results of phase-resolved micro-BLS 

experiments relative to the SWs emitted by a coplanar waveguide in a permalloy layer.The wavelength of the excited SWs 

is measured and successfully compared to the results of micromagnetic simulations, taking into account the spatial characteristics 

of the exciting waveguide. 

This work was supported by CNISM under -BLS Innesco 2006 Project and by the European Community‘s Seventh Framework 

Programme (FP7/2007-2013) under Grant Agreement n°228673 (MAGNONICS). 

References 

[1] M. Madami, S. Bonetti, S.Tacchi, G. Carlotti, G. Gubbiotti, G. Consolo, F. Mancoff, M.A. Yar, and J. Åkerman, Nat. 

Nanotech. 6, 635 (2011). 

giovanni.carlotti@fisica.unipg.it


Spin-torque oscillators c03-c 

Transfering magnetic vortices between many spin torque oscillators 

Mauricio Manfrini 1 , Joo-Von Kim 2 , Sébastien Petit-Watelot 2 , Ruben Otxoa 2 , Claude Chappert 2 , Win Van Roy 1 , 

Laith Altimime 1 , Jorge Kittl 1 , Liesbet Lagae 1 , Thibaut Devolder 3 

1 Interuniversity Microelectronics Center, B-3001 Leuven, Belgium 

2 Institut d‘Electronique Fondamentale, 91405 Orsay, France 

3 CNRS, Université Paris-Sud, 91405 Orsay, France 

„Vortexonics“ is the art of manipulating of magnetic vortices. A model playground for vortexonics is a metallic 

nanoscale contact injecting electrical current into a multilayer. Indeed the magnetic field associated with the charge 

flow can prepare a vortex on demand, which is subsequently set into planetary revolution about the nanocontact by 

the spin flow and the related transfer of angular momentum between the layers‘ magnetizations. Through the magneto-resistance, 

the spinning vortex induces an oscillation of the nanocontact resistance, with foreseen applications 

to compact microwave sources of exceptional agility, instant-on capability, low phase noise and multi-octave frequency 

coverage. When instead of a single nanocontact, chains or complicated patterns comprising multiple nanocontacts 

sharing the same multilayer are used and addressed with independent currents, this yields an even richer vortex 

dynamics. The peculiarly of the non parabolic attracting potentials supplied by the charge flow and non conservative 

forces supplied by the spin flow in the set of nanocontacts ensures the presence of a single spinning vortex in the 

system. Playing with the adjustable attracting potentials of neighbouring nanocontacts, we show experimentally 

and model theoretically that the vortex can be ordered to swap position between the neighbouring nanocontacts, 

as proven from the microwave signals radiated by each of the nanocontacts. Time-resolved experiments show that 

this relocation of the vortex can be faster than 5 ns, in agreement with micromagnetic modeling. In high current 

conditions, the vortex can also orbit along a path that surround several nanocontacts. This opens routes for the 

coherent guiding of a single magnetic vortex in interconnected chains of nanocontacts, and to manipulate the vortex 

and have it interact with other high energy magnetic pseudo-objects. 

thibaut.devolder@u-psud.fr 

61


62 


Switching voltages and back-hopping in magnetic tunnel junctions with different 

geometries 

Kerstin Bernert, Volker Sluka, Ciaran Fowley, Huadong Gan, Jürgen Fassbender, Alina M. Deaci 

Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany 

A spin-polarized current flowing through a ferromagnet can exert a torque on the local magnetization [1,2], which can 

induce switching or steady state precession. Spin-transfer switching can be used as writing scheme in magnetic random 

access memory (MRAM), while spin-torque-driven precession can be exploited to design RF oscillators for telecommuni- 

cation devices. Presently, the majority of spin-torque devices are based on a magnetic tunnel junction (MTJ) with an MgO 

barrier.A key step towards the practical implementation as MRAM elements is the reduction of the critical voltages [3]. 

Several groups have reported that MTJs exhibit the so-called ‘back-hopping’, whereby reliable switching is achieved with 

voltages of the order of the switching voltage, while a larger applied bias induces a telegraph-noise behaviour [4,5]. 

Back-hopping is characteristic for MTJs, since it has not been observed in metallic multilayers, and raises concerns for 

designing industrially-competitive MRAM devices. Here, we demonstrate that a potential cause for this phenomenon is 

the field-like (out-of-plane) spin-torque, which has been found to be much larger in MgO-MTJs than in metallic spin-valves, 

where it can be neglected [6]. In MgO-MTJs, however, the field-like torque can be of the order of 30% of the in-plane 

torque [7], and needs to be taken into account. We evaluate the switching phase diagram by analytically and numerically 

solving the modified Landau-Lifshitz-Gilbert equation which includes both (in-plane) (Slonczewski-like) and field-like torque 

terms for different geometries. The quadratic dependence of the field-like torque on the applied voltage [8] translates 

into a more complex correlation between the critical bias and the external field, altering the shape of the phase diagram 

as demonstrated experimentally [9]. It also explains back-hopping at a large bias for specific geometries, in agreement 

with experimental results. 

References 

[1] J. C. Slonczewski, J. Magn. Magn. Mater. 159, L1 (1996). 


[3] Z. Diao et al., J. Phys.: Cond. Mat. 19, 165209 (2007). 

[4] J. Z. Sun et al., J.Appl. Phys. 105, 07D109 (2009). 

[5] T. Min et al., J.Appl. Phys. 105, 07D126 (2009). 

[6] M.A. Zimmler et al., Phys. Rev. B 70, 184438 (2004). 

[7] J. C. Sankey et al., Nat. Phys. 4, 67 (2008). 

[8] C. Heiliger and M. Stiles, Phys. Rev. Lett. 100, 186805 (2008). 

[9] S. C. Oh et al., Nat. Phys. 5, 898 (2009). 

k.bernert@hzdr.de


Magnon Spintronics and caloritronics c05-I 


Using spin waves to probe spin-polarized electron transport 


IPCMS CNRS/Université de Strasbourg, 67034 Strasbourg, France 

The interplay between magnetization dynamics and spin-polarized electron transport is at the heart of modern spintronics. 

The spin waves can be used to probe accurately this interplay. As an example of this approach, we have 

observed in 2008 an effect called current-induced spin-wave Doppler shift:[1] When an electrical current flows along 

a ferromagnetic metal, it induces a motion of the magnetic system which directly translates into a Doppler shift for 

the spin waves. 

In this talk, I will show how the current-induced Doppler shift can be extracted from high resolution measurements 

of propagating spin wave spectroscopy.[2] Then I will show how a key parameter of spin-polarized transport –the 

current spin-polarization- can be extracted from the measured Doppler shift. Finally I will discuss how recent measurements 

carried in Strasbourg and in other groups could shed a new light onto old questions in the field of spinpolarized 

transport. 

References 

[1] V. Vlaminck and M. Bailleul, Science 322, 410 (2008). 

[2] V. Vlaminck and M. Bailleul, Phys. Rev. B 81, 014425 (2010). 

bailleul@ipcms.u-strasbg.fr 

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64 

Magnon Spintronics and caloritronics c06-I 


Domain wall dynamics and the magnonic spin Seebeck effect 

Denise Hinzke, Ulrike Ritzmann, Ulrich Nowak 

Universität Konstanz, 78457 Konstanz, Germany 

Recently, it has been demonstrated that in ferromagnetic insulators spatial temperature gradients can lead to magnon 

accumulation [1]. This underpins the fact that in addition to spin polarized charge currents due to electron motion also 

chargeless angular momentum currents driven by spin waves can exist. The latter current leads to pure magnonic effects 

without any electron currents involved. 

We investigate the existence of domain wall dynamics driven by magnonic spin currents due to temperature gradients. 

To get some insight into this new effect two different approaches for the simulation of coupled thermo-magnetic properties 

are introduced: the stochastic Landau-Lifshitz-Gilbert equation, applied to atomistic spin models, and the Landau-Lifshitz- 

Bloch equation describing the dynamics of the thermally averaged spin polarization on micromagnetic length scales. 

We find a new type of domain wall dynamics, where pure spin currents following from a temperature gradient drag 

a domain wall into the hotter region. In the limit of low damping constants and large temperature gradients this domain 

wall motion is accompanied by precession and a Walker breakdown exists [2]. 

Continuing our investigation of domain wall dynamics driven by temperature gradients we focus on a better understanding 

of the relevant length scales. We explore the propagation of thermally induced magnons, the magnon accumulation, and 

calculate the magnon temperature for given phonon temperature profiles. 

We acknowledge financial support by the DFG through SFB 767 and through SPP “Spin Caloric Transport”. 

References 

[1] K. Uchida et al., Nat. Mater. 9, 894 (2010). 

[2] D. Hinzke and U. Nowak, Phys. Rev. Lett. 107, 027205 (2011). 

denise.hinzke@uni-konstanz.de


Magnon Spintronics and caloritronics c07-c 

Evidence of a strong magnetoelectric effect in a FeCoB/PMN-PT bilayer at microwave 

frequencies 

Vincent Laur 1 , Patrick Queffelec 1 , Faliniaina Rasoanoavy 1 , Gor Lebedev 2 , Bernard Viala 2 , Mai Pham-Thi 3 

1 Lab-STICC / UBO, 29238 Brest, France 

2 CEA LETI, 38054 Grenoble, France 

3 Thales Research & Technology, 91404 Orsay, France 

Due to the growing needs in multistandard and miniature microwave devices, the research of tunable materials 

became a burning issue in the last few years. In this way, magnetoelectric structures recently appear as a promising 

option to ferroelectrics-, or ferromagnetics-based devices. In this study, we investigated a hybrid magnetoelectric 

structure constituted of a FeCoB ferromagnetic film deposited on a PMN-PT single crystal. The piezoelectric substrate 

acts here as an actuator to generate strains in the magnetic films. Due to their magnetostrictive properties, an 

induced-magnetic field appears in the ferromagnetic layer which modifies its magnetization state. Indeed, a change 

of permeability can be obtained by the application of an electric field (i.e. a magnetoelectric effect). 

At first, we studied the static properties of a 75-nm thick (Fe Co ) B film deposited on a glass substrate through 

65 35 80 20 

VSM measurements. A strong anisotropy of the FeCoB magnetic properties was observed on this substrate. This film 

presents a high level of saturation magnetization (4πMS = 10 kG) and a low anisotropy field (H = 20 Oe) leading to 

k 

a natural gyromagnetic resonance frequency fr of 1.5 GHz and a dc initial permeability µdc of about 600 measured at 

microwave frequencies using a microstrip permeameter. 

We then studied a (Fe Co ) B /glass bilayer. This film presents a significantly higher resonance frequency than the 

50 50 86 14 

first studied composition (f = 2.6 GHz) that allows a larger frequency band of application. 

r 

Similar film was thus deposited on a PMN-28PT single crystal. The microwave magnetic properties of the film were 

similar to the ones observed on FeCoB/glass bilayer (i.e. µ = 400, f = 2.67 GHz, strong anisotropy). The permeability 

dc r 

spectrum of the film was then measured as a function of bias voltage. A cancellation of the magnetic properties 

(µ = 1) was observed for a bias voltage of 125 V (3.1 kV/cm) demonstrating thus a strong magnetoelectric coupling 

dc 

at microwave frequencies in the structure. 

Our main objective is to apply this effect to tunable phase shifters or antennas. 

vincent.laur@univ-brest.fr 

65


66 

Magnon Spintronics and caloritronics c08-c 

Attenuation of propagating spin wave induced by layered nanostructures 

Koji Sekiguchi 1 , Taco Vader 2 , Keisuke Yamada 3 , Shunsuke Fukami 4 , Nobuyuki Ishiwata 5 , Soo-man Seo 5 , 

Seo-won Lee 5 , Kyung-jin Lee 5 , Teruo Ono 6 

1 Keio University, 223-8522 Yokohama, Japan 

2 Eindhoven University, 5600MB Eindhoven, Netherlands 

3 University of Paris-Sud, 91405 Orsay, France 

4 NEC Corporation, 305-8501 Tsukuba, Japan 

5 Korea University, 136-701 Seoul, Korea 

6 Kyoto University, 611-0011 Uji, Japan 

Magnon-spintronic circuits harnessing spin-wave propagation have been of great interest for signal processing in virtue 

of ultrafast propagation and low power consumption.The spin-wave logic gates have been recently demonstrated by using 

the Mach-Zehnder interferometer with yttrium iron garnet (YIG) waveguides. Since the YIG is not compatible with standard 

silicon integrated circuit (IC) technology, spin wave propagation in IC-compatible materials such as FeNi is of importance for 

the realization of integrated circuits. The magnetostatic surface wave (MSSW) in the FeNi film is the promising mode due 

to its high propagation velocity and a non-reciprocal character. For the control of spin wave amplitude after the emission, 

spin wave attenuation in the layered FeNi/Pt thin films was investigated by the time-domain electrical measurement. 

The time-resolved propagating spin wave spectroscopy (PSWS) was carried out for the [Fe 17 Ni83/Pt] 6 /Fe 17 Ni 83 multilayer 

stacks patterned into 120 µm × 100 µm stripes. The multilayered spin-wave medium was grown by magnetron sputtering 

on intrinsic silicon substrates. The thickness of Pt layer in medium was changed from 0.06 to 0.6 nm, much thinner than 

the spin diffusion length. Spin waves (MSSW) are excited and detected with a pair of asymmetric coplanar strip (ACPS) 

transmission lines placed on the film. With increasing the Pt content from 0 % to 10 %, the attenuation length of MSSW 

is systematically decreased from 13 µm to 6.5 µm: the amplitude of a spin-wave packet was systematically changed by 

controlling the thickness of a platinum layer, up to a maximum change of 50 %. The virtues of spin wave, ultrafast 

propagation velocity 11.7 km/s and non-reciprocal emission, are preserved in this manner. This means that the Pt layer 

can manipulate an arbitral power-level of spin-wave input signal (reliable attenuator), leading to the spin-wave function 

as a signal attenuator for logical spin-wave circuits. 

K.S. acknowledges financial support from JST-PRESTO.T.O. acknowledges financial support from MEXT. K.J.L. acknowledges 

financial support from the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST). 

koji_s@phys.keio.ac.jp


Magnetization dynamics and Relaxation c09-I 


Coherent magnetization dynamics investigated with magneto-optical four wave 

mixing in a garnet film 

Marie Barthelemy, Monica Sanches Piaia, Mircea Vomir, Michele Albrecht, Jean-Yves Bigot 

IPCMS-DON, 67034 Strasbourg, France 

Different approaches are trying to explain the loss of spin angular momentum induced by ultrashort pulses in magnetic 

materials. One of them considers the coupling between photon and spin momenta. Several studies have focused 

on the study of the coherent magneto-optical response which is the primary process preceding the ultrafast demagnetization 

in ferromagnetic materials. Such coherent processes are important to investigate with the perspective 

of manipulating coherently the magnetization of magnetic materials. Recently it has been shown [1] that, prior to 

the known incoherent demagnetization that accompanies the thermalization of the spins [2], a coherent response 

is present in the pump-probe Faraday or Kerr magneto-optical signals. This coherent contribution has to be distinguished 

from the subsequent thermal dynamics that corresponds to spin population relaxation. It is related to the 

coupling between the spins and the electric potential associated to the laser electric field [3]. However in pump-probe 

magneto-optical configuration, it is difficult to extract the pure coherent component. 

In the present work, we show that the well known Four Wave Mixing (FWM) technique, that intrinsically isolates the 

coherent contribution due to the charges in a nonlinear medium, can be used as a tool for studying the coherent 

magnetization dynamics. It consists in measuring the FWM emission by applying a static magnetic field and analysing 

its time dependent rotation of polarisation. Magneto-Optical Four-Wave mixing (MO-FWM) experiments were 

performed on a Garnet film deposited on a GGG substrate by liquid phase epitaxy. It is an ideal system for this study 

since it is transparent in the near infrared, therefore allowing for FWM emission with minimum absorption. Firstly, in 

a two beam MO-FWM configuration, the magnetization dynamics present in the FWM signal is compared to the time 

dependent Faraday configuration that is simultaneously observed. The coherent contribution to the magneto optical 

response shows up very well, as it is followed by the thermal dynamics present in the Faraday signal. It depends on 

the applied static magnetic field and corresponds to the emission of a coherent magneto-optical wave. In a second set 

of experiments, we demonstrate that the three beams MO-FWM configuration can also be used to measure separately 

the coherent and the population dynamics including precession of magnetization. Details concerning the respective 

role of the coherent and population dynamics of the spins in the magneto-optical response will be reviewed and 

discussed. 

This work was supported by the European Research Council: project Atomag, ERC-2009-AdG-20090325 #247452 

References 

[1] J.-Y. Bigot, M. Vomir, and E. Beaurepaire, Nature Phys. 5, 515(2009). 

[2] L. Guidoni, E. Beaurepaire, and J.-Y. Bigot, Phys. Rev. Lett. 89, 17401 (2002). 

[3] H. Vonesch and J.-Y. Bigot, Phys. Rev. B 85, 180407 (2012). 

marie.barthelemy@ipcms.unistra.fr 

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68 

Magnetization dynamics and Relaxation c10-c 

Excitation of magnetic dynamics by the spin-orbit interaction 

Hidekazu Kurebayashi 1 , Dong Fang 1 , Andrew Ferguson 1 , Oleksandr Dzyapko 2 , Vladislav Demidov 2 , 

Sergej Demokritov 2 

1 University of Cambridge, CB3 0HE Cambridge, UK 

2 University of Münster, 48149 Münster, Germany 

We can find in nature some scattering processes that change the total angular momentum of involved (quasi-) particles. In 

this talk, I would like to present this type of scattering occurring in a conduction carrier system and its applications for spintronics.When 

the spin-orbit (SO) interaction is sufficiently strong the dispersion relationship of conduction carriers depends 

on the spin orientation. This causes the change in total spin angular momentum of carrier system when applying an electric 

field to the carriers. In a conductive ferromagnet where the conduction electrons’ spins couple to the localised spins via the 

exchange interaction, the applied electric field can therefore create an internal magnetic field. Using this mechanism at GHz 

frequencies, we induced magnetic torques in a GaMnAs micro-bar [1], which drives ferromagnetic resonance. Several sets 

of the experiments revealed that the magnitude and the symmetry of the excitation field, which will be compared with a 

microscopic model. Although this demonstration was carried out by using the high SO dilute semiconductor, the technique 

can be transferable to magnetic dynamics in some metal systems, e.g ultra-thin Co with the Rashba SO effect [2]. 

References 

[1] D. Fang, H. Kurebayashi, J.Wunderlich, K.Výborný, L. P. Zârbo, R. P. Campion,A. Casiraghi, B. L. Gallagher,T. Jungwirth, and 

A. J. Ferguson, Nature Nanotech. 6, 413 (2011). 

[2] I. M. Miron et al., Nature 476, 189 (2011). 

hk295@cam.ac.uk



Spin torque vortex oscillation properties in CPP-GMR devices with perpendicular 

[Co/Pd]n spin injector 

Yuki Kawada, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando 

Tohoku University, 980-8579 Sendai, Japan 

Spin torque vortex oscillator (STVO) using perpendicular spin injector and in-plane magnetization free layer has at- 

tracted attention from the viewpoint of microwave application because of coherent oscillation mode (high Q-factor) 

owing to the homogenous spin-transfer torque during oscillation can expect. It was theoretically suggested that 

perpendicular spin injector excites the vortex resonance mode at the in-plane free layer without an external magnetic 

field [1]. In this study, we fabricated STVO devices having a [Co/Pd]n spin injector and NiFe free layer, and experimen- 

tally demonstrated STVO properties without the external magnetic field. 

The CPP-GMR device were deposited onto thermally oxidized Si(001) wafers using an ultrahigh vacuum 

(P base < 3×10 -6 Pa) magnetron sputtering system. The stacking structure of the multilayer was as follows: Si/SiO 2 sub./ 

Ta (5)/Ru (50)/[Pd (0.4)/Co (0.2)]4/Cu (3)/Co 75 Fe 25 (1.5)/Ni 80 Fe 20 (15)/Ru (7) (in nm). All the films were grown at RT. 

Electron-beam lithography and Ar ion milling were employed to form the nano-pillar with a 100 × 100 nm 2 circular 

cross-section. STO was measured using spectral analyzer under the out-of-plane magnetic field. 

The current dependence of microwave spectra under 300 Oe for out-of-plane direction has been measured. A signal 

appeared from 11.8 mA and the oscillating frequency increased with increasing current. Above 13.2 mA, the STO 

signal was split into two signals and a sharp STVO signal was observed around 4.5 GHz over 15.6 mA. The signal 

observed around 1 GHz is due to a vortex core oscillation and the switching whereas the signal around 4.5 GHz is 

speculated to be a standing spin wave mode associated with the vortex core switching or the phase change of the 

vortex. Next, the dependence of the oscillating frequency on magnetic field has been measured. We successfully observed 

a STVO signal without magnetic field.This is the first report of the vortex self-oscillations using a perpendicular 

spin injector under zero-field. And Q-factor was 200, which is comparable with the reported maximum value under 

zero-field [2]. The frequency shift due to the magnetic field was small. These results showed that spin-transfer torque 

due to the perpendicular spin injector is efficient for obtaining a high Q-factor without an external magnetic field. 

This work was partly supported by Strategic Japanese-German cooperative program (ASPIMATT) from JST. 

References 

[1] Y. Liu et al., Appl. Phys. Lett. 91, 242501 (2007). 

[2] V. S. Pribiag et al., Nature Phys. 3, 498 (2007). 

y.kawada@mlab.apph.tohoku.ac.jp 

marie.barthelemy@ipcms.unistra.fr 

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70 


Revealing the significance of heating in the all-optical switching process 

Sabine Alebrand, Daniel Steil, Mirko Cinchetti, Martin Aeschlimann 

Deptartment of Physics, University of Kaiserslautern, 67663 Kaiserslautern, Germany 

It is well known that it is possible to switch the magnetic state of a ferrimagnetic GdFeCo sample all-optically, i.e. just by 

using one single circularly polarized laser pulse and without any additional external magnetic field [1]. In principle the laser 

pulse may fulfil two functions: delivering helicity and heating up the sample. Up to now it is still controversially discussed in 

literature if heating is necessary for the all-optical switching process [2,3]. 

To shed light on this issue: (i) we consider the dependence of the minimum laser fluence needed to obtain switching on 

the repetition rate of the laser pulses; and (ii) discuss the results of ρ-π experiments using one circularly pulse (acting as 

angular momentum source) and a linearly polarized pulse (acting as a heating pulse).We show that it is possible to switch 

all-optically by the combination of both pulses although the fluence of the circularly polarized laser pulse is below the 

minimum fluence threshold (determined for switching with only one circularly polarized pulse). Both of our experiments [4] 

clearly favour the fact that heating contributes to the switching process. 

References 

[1] Stanciu et al. Phys. Rev. Lett. 99, 047601 (2007). 

[2] Kirilyuk et al., Rev. of Mod. Phys. 82, 2731 (2010). 

[3] D. Steil, S.Alebrand,A. Hassdenteufel, M. Cinchetti, and M.Aeschlimann, Phys. Rev. B 84, 224408 (2011). 

[4] S.Alebrand,A. Hassdenteufel, D. Steil, M. Cinchetti, and M.Aeschlimann, Phys. Rev. B 85, 092401 (2012). 

alebrand@rhrk.uni-kl.de



Ultrafast magneto-acoustics using femtosecond laser pulses 

Jiwan Kim 1 , Mircea Vomir 2 , Jean-Yves Bigot 2 

1 CNRS, 67034 Strasbourg, France 

2 IPCMS-DON, 67034 Strasbourg, France 

We report about the magnetization dynamics of a nickel film at room temperature induced by acoustic pulses excited 

with femtosecond laser pulses. The propagation of acoustic pulses modifies the magnetic anisotropy and causes the 

change of magnetization dynamics. The ultrafast changes of the magnetization are measured from both the front and 

back sides of the film through the pump-probe magneto-optical Kerr technique. On the front side, the small changes 

of the magnetization induced by acoustic echoes are superimposed on the large precessions due to thermal excitation 

of pump pulses. Compared to this, on the back side, the precession of the magnetization, which is initiated only by 

the acoustic pulse, shows better contrasts on magneto-optical responses and interesting features that the precession 

motion is influenced by following acoustic echoes. We model the time-dependent magneto-acoustic response 

by combining a three temperature model for the temperatures of the electrons, the spins, and the lattice, the wave 

equation for the acoustic pulse, and the Landau-Lifshitz-Gilbert (LLG) equation for the magnetization. Our model 

quantitatively explains well the magnetization dynamics induced by acoustic pulses at both sides of the film and 

manifests the possibility that the adequate combinations of acoustic pulses can efficiently manipulate the precession 

of the magnetization. 

In order to explore details about the controllability of the magnetization by acoustic pulses, we calculated from LLG 

equation the change of the precession torque which is defined as the difference between the value of the torque 

after the 0th and 1st order acoustic echoes arriving at the back side of the film. From the calculation, the change of 

the torque depends on the phase of the precession when the echo arrives. The maximum (minimum) change of the 

torque occurs whenever the round trip time T , the time difference between two successive echoes, of the acoustic 

R 

pulse corresponds to the even (odd) multiples of the half period of the precession T P /2, that is T R = mT P ((2m-1)T P /2). 

This means that the precession amplitude of the magnetization can be controlled by a particular sequence of acoustic 

pulses. This calculation explains well our experiment data measured at two different angles of the static magnetic 

field to control T , where the precession amplitude was either enhanced or diminished. Therefore, it is anticipated that 

P 

the perturbation efficiency by acoustic pulses can be maximized for the amplification or minimized for the stop of ringing 

of the precession. Our results open a new way of controlling magneto-acoustic devices at room temperature [1]. 

The authors acknowledge financial support from the European Research Council project: ERC Advanced Grant 

ATOMAG (ERC-2009-AdG-20090325 247452). 

References 

[1] Ji-Wan Kim, Mircea Vomir, Jean-Yves Bigot, arXiv:1201.0170v1 and submitted to Phys. Rev. Lett. 

hwoarang.kim@gmail.com 

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72 



Magnetization dynamics in micro-dots driven by magnetic field and spin-transfer 

torque 

Sergej Demokritov, Vladislav E. Demidov 

University of Münster, 48149 Münster, Germany 

In this talk I report our recent experimental results on linear and nonlinear magnetization dynamics in individual microscopic 

Permalloy dots subjected to microwave-frequency magnetic field or spin-transfer torque produced by the spin Hall effect. 

The experiments were performed using Brillouin light scattering (BLS) spectroscopy, which allows two-dimensional mapping 

of the dynamic magnetization with the spatial resolution down to 50 nm and the temporal resolution down to 1 ns. 

I show that under conditions of microwave-field excitation, the microscopic dots demonstrate a large variety of nonlinear 

phenomena, such as mode hybridization and competition, nonlinear magnon scattering, resonant frequency multiplication, 

and parametric spin-wave instability. Due to the strong concentration of the driving dynamic field in a microscopic volume, 

these effects can be observed at moderate microwave powers, which makes the studied structures promising for applications 

associated with processing of microwave signals on the microscopic scale. 

I also show that the magnetization dynamics in Permalloy micro-dots can be strongly influenced by injection of pure spin 

currents created using the spin Hall effect. In particular, I demonstrate that spin currents can be used to efficiently suppress 

or enhance thermal magnetic fluctuations, vary the dynamic magnetic damping, and control the characteristics of parametric 

processes. These effects enable controllable reduction of high-frequency magnetic noise and high-frequency losses in 

magnetic nano-devices. They also open a route to the implementation of novel magnetic nano-oscillators driven by pure 

spin currents. 

References 

V. E. Demidov et al., Phys. Rev. Lett. 104, 217203 (2010). 

J. Jersch et al.,Appl. Phys. Lett. 97, 152502 (2010). 

V. E. Demidov et al., Phys. Rev. B 83, 020404(R) (2011). 

H. Ulrichs et al., Phys. Rev. B 83, 184403 (2011). 

V. E. Demidov et al., Appl. Phys. Lett. 99, 012505 (2011). 

V. E. Demidov et al., Phys. Rev. Lett. 107, 107204 (2011). 

V. E. Demidov et al., Appl. Phys. Lett. 99, 172501 (2011). 

demidov@uni-muenster.de




Magnetic droplets in nano-contact spin torque oscillators with perpendicular 

anisotropy free layers 

Johan Åkerman 1,2 , Majid Mohseni 2 , Johan Persson 3 , Sohrab Sani 2 , T. N. Anh Nguyen 2 , Sunjae Chung 2 , 

Yevgen Pogoryelov 1 , Pranaba Muduli 1 , Alina M. Deac 4 , Mark Hoefer 5 

1 Physics Department, University of Gothenburg, 41296 Gothenburg, Sweden 

2 KTH - Royal Institute of Technology, 16440 Kista, Sweden 

3 NanOsc AB, 16440 Stockholm, Sweden 

4 Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany 

5 Department of Mathematics, North Carolina State University, 27695 Raleigh, USA 

Ivanov and Kosevich showed, 35 years ago, that if damping is ignored, the Landau-Lifshitz equation for an extended 

2-dimensional magnetic thin film with perpendicular magnetic anisotropy (PMA) can sustain a family of conservative 

magnetic solitons [1,2]. Hoefer et al recently predicted that a dissipative version of these solitons, a so-called „magne- 

tic droplet“, should be possible to sustain in nano-contact spin torque oscillators (NC-STOs) with PMA [3].The magne- 

tic droplet should be a localized and dynamically stabilized oscillating mode with rich magnetodynamic properties [4]. 

In this work, we present the first experimental observation indicating the existence of such a localized dissipative 

droplet soliton mode in NC-STO with a free layer with strong PMA. Nano-contacts, with diameters ranging from 50 to 

100 nm, were fabricated on top of an orthogonal spin valve with in-plane Co reference layer and PMA Co/Ni free layer 

separated by a Cu spacer: Co /Cu/Co [Ni /Co ]x4, with thicknesses given in nm. We recently demonstrated high- 

8 0.3 0.8 0.4 

frequency and low-field operation of such NC-STOs [5], confirming the large PMA of the free layer. Here, we explore 

the magnetodynamic properties of these devices at significantly larger out-of-plane magnetic fields. As expected, we 

first observe a linear field dependence of the NC-STO frequency. However, at a moderately high field of about 0.65 

T the NC-STO frequency exhibits a dramatic drop of about 10 GHz, accompanied by a sharp increase in the device 

resistance. These sharp transitions could also be observed as a function of NC-STO current in a fixed field. Above the 

transition, we find a very rich dynamics with the observation of auto-modulation and strong signals at half the fundamental 

frequency. We argue that the observed transitions indicate the formation of a magnetic droplet underneath 

the nano-contact and we show how the relation between nano-contact size, droplet onset frequency, droplet onset 

field and current, as well as total frequency drop fit well with theory. Micromagnetic simulations identify the automodulations 

with lower-frequency oscillatory motion of the entire droplet and the oscillations at half the fundamental 

frequency as “breather” states involving synchronized droplet perimeter deformations. 

References 

[1] B. A. Ivanov and A. M. Kosevich, Zh. Eksp. Teor. Fiz. 72, 2000 (1977). 

[2] A. M. Kosevich, B. A. Ivanov, and A. S. Kovalev, Phys. Rep. 194, 117 (1990). 

[3] M. A. Hoefer, T. J. Silva, and M. W. Keller, Phys. Rev. B 82, 054432 (2010). 

[4] M. A. Hoefer and M. Sommacal, Physica D 241, 890 (2012). 

[5] S. M. Mohseni, S. R. Sani, J. Persson, T. N. Anh Nguyen, S. Chung, Ye. Pogoryelov, and J. Åkerman, Phys. Stat. Sol. 

RRL 5, 432 (2011). 

johan.akerman@physics.gu.se 

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74 


Origin and consequence of mode hopping in a magnetic tunnel junction based spin 

torque oscillator 

Pranaba Muduli 1 , Olle G. Heinonen 2 , Johan Åkerman 1 

1 University of Gothenburg, 41296 Gothenburg, Sweden 

2 Materials Science Division and Department of Physics and Astronomy,Argonne National Laboratory and Northwestern 

University, Lemont, IL 60439, USA 

Current flowing through a magnetic material can alter its magnetization by spin torque [1]. This mechanism can induce 

high-frequency precession of magnetization.A fundamental question regarding this precession is the stochastic phenomena 

that govern its coherence time. This is a subject of significant interest recently. Until now theoretical studies have investigated 

de-coherence through thermal noise assuming that only a single mode is excited [2]. On the other hand, experiments 

clearly show both the existence of multiple modes and persistent mode-hopping between several modes. The impact on 

coherence time of such mode hopping has been largely unexplored and a theoretical study of its origin is entirely lacking. 

In this work, we will present first ever systematic experimental investigations of mode-hopping, and its impact on coherence 

time in a magnetic tunnel junction based spin torque oscillator (STO) [3]. We will discuss micromagnetic simulations and 

a theoretical treatment to show that the non-conservative fields due to finite damping - either positive or negative (spin 

torque) - couple individual modes and, in the presence of thermal noise, govern the experimentally observed mode hopping. 

The coupling has an angular dependence which explains the experimentally observed angle dependent mode-hopping. 

Finally we will present a quantitative analysis of both coherence and dwell times, and show that mode-hopping could be a 

limiting factor for STO coherence at some cases. Nevertheless, the existing theory of single-mode STO [2] qualitatively holds 

when the dwell time is sufficiently larger than the coherence time of the oscillations. 

Support from the Swedish Foundation for strategic Research and the Swedish Research Council is gratefully acknowledged. 

Johan Åkerman is a Royal Swedish Academy of Sciences Research Fellow supported by a grant from the Knut and Alice 

Wallenberg Foundation.Argonne National Laboratory (ANL), a US DOE Science Laboratory operated under contract no. DE- 

AC02-06CH11357 by UChicago Argonne, LLC. 

References 

[1] J. C. Slonczewski, J. Magn. Magn. Mat. 159, L1 (1996); L. Berger, Phys. Rev. B 54, 9353 (1996). 

[2] A. Slavin and V.Tiberkevich, IEEE Trans. Magn. 45, 1875 (2009). 

[3] P. K. Muduli, O. G. Heinonen, and J. Åkerman, Phys. Rev. Lett. 108, 207203 (2012). 

pranabmuduli@gmail.com



Frequency generation by a magnetic vortex-antivortex dipole in spin-polarized current 

Stavros Komineas 

University of Crete, 71409 Heraklion, Greece 

The issue of magnetic vortex dynamics has been dramatically raised anew by recent experimental observations where 

GHz frequencies were measured.We study vortex oscillations using the Landau-Lifshitz-Gilbert-Slonczewski equation. 

We assume that spin-polarized current is injected through a nano-aperture on the top surface of an element, with 

in-plane spin-polarization. 

We assume a vortex-antivortex (VA) pair where the vortex and the antivortex have opposite polarities. This vortex 

dipole has the structure of a skyrmion with skyrmion number N = 1. We derive an exact(virial) relation through which 

we interpret the skyrmion rotational motion as the result of two independent forces: the interaction between the two 

vortices and an external in-plane magnetic field.The latter can be used to tune the frequency of rotation.The nonzero 

skyrmion number of the vortex dipole is responsible for both forces giving rise to rotational motion. We find, through 

numerical simulations, that the spin-torque acts to stabilize the motion. This results in a simple steady-state when we 

take into account the exchange interaction and an easy-plane anisotropy. 

A series of numerical simulations show that the VA pair typically rotates outside the nano-aperture. The VA distance 

depends on the strength of the spin-polarized current.We calculate numerically the angular momentum and the total 

magnetization of the magnetic structure and explain, through the virial relation, their relation to the frequency of 

rotation. We show how the frequency can be tuned by system parameters, so as to produce an STNO. The present 

results can be used as a framework for the description of frequency generation by topological solitons under spinpolarized 

current. 

References 

EPL 98, 57002 (arXiv:1203.0880) (2012). 

komineas@tem.uoc.gr 

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76

ABSTRAcTS – Posters 

77


78 

high Frequency Materials P01 

Poster 

Double resonance behavior of FeCo/(FeCo) 0.63 (SiO 2 ) 0.37 multilayer on flexible 

substrates 

Li Zhang 1,3 , Peiheng Zhou 1,2,3 , Mangui Han 1,2,3 , Jianliang Xie 1,2,3 , Longjiang Deng 1,2,3 

1 Engineering Research Center of Electromagnetic Wave Absorbing Materials, Ministry of Education, 

Chengdu 610054, China 

2 State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and 

Technology of China, Chengdu 610054, China 

3 University of Electronic Science and Technology of China, Chengdu 610054, China 

With the development of highly integrated electronic devices, magnetic thin film because of their special structure 

characteristics and free from Snoek limitation has been intensively studied in the past years. To our knowledge, 

obtaining wide frequency band imaginary of the microwave permeability is beneficial to high frequency applica- 

tion. Multiresonance phenomena which can large bandwidth have been observed in nanocrystalline FeCoNi flakes 

composite [1], Co nanoflake [2] and multiwalled carbon nanotubes (MWCNTs) [3] which could be well explained 

according to the exchange resonance mode proposed by Aharoni [4]. However, it is hard to observe multiresonance 

in an experimental permeability dispersion spectrum and usually, only one dispersion is found in the -spectrum for 

magnetic granular thin films. 

In this letter, we report the double resonance behavior of microwave magnetic permeability has been observed for 

[FeCo/(FeCo) (SiO ) ] multilayer magnetic thin films with different FeCo layer thickness on flexible substrates. 

0.63 2 0.37 X 

The double resonance mechanism of multilayer are studied. One of them is attributed to the natural resonance 

and another is considered to originate from the exchange energy of the nanograins. The calculated results were 

close to the experiment. It is believed that the coexistence of double resonance is beneficial to large bandwidth as 

a microwave absorber. 

References 

[1] L. J. Deng, P. H. Zhou, J. L. Xie, and L. Zhang, J. Appl. Phys. 101,103916 (2007). 

[2] F. Ma, Y. Qin, and Y. Z. Li, Appl. Phys. Lett. 96, 202507 (2010). 

[3] F. S. Wen, H. B. Yi, L. Qiao et al., Appl. Phys. Lett. 92, 042507 (2008). 

[4] A. Aharoni, J. Appl. Phys. 69, 7762 (1991). 

lzhang129@uestc.edu.cn


Poster 

Microwave permeability of single cobalt nanotubes studied by the generalized 

Snoek’s law 

Mangui Han 1 , Ravi Hadimani 2 , Longjiang Deng 3 

1 State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of 

China, 610054 Chengdu, China 

2 Department of Electrical and Computer Engineering, Iowa State University,Ames, IA 50011, USA 


Recently, there is an increasing interest in studying the dynamic magnetic properties of nanostructured elements. For in- 

stance, novel self-biased microwave circulators have been proposed [1].The dynamic permeability spectrum of nanotube is 

important in both fundamental and applications. One attribute that makes this property desirable is that the eddy current 

loss interfering with permeability spectrum is greatly suppressed for nanotubes due to the special hollow structure. Another 

reason is that the resonance frequency of nanotubes can be tuned by varying the aspect ratio. Here, using the micromagnetism 

simulation, we report the dynamic permeability of single Co nanotube in the remanent state with the inner diameter, 

outer diameter and the length to be 50 nm, 100 nm and 600 nm respectively. Four strong magnetic loss peaks have been 

found at 11.72, 24.20, 33.18 and 39.55 GHz, which are different from that of single Co nanowire with only two magnetic 

loss peaks. The different magnetic moments configurations along the nanotube are believed for this observed difference. 

O.Acher et al have proposed a generalized Snoek’s law for the magnetic thin films and composites, in which the integral of 

[µ“ x f ] is bounded by the square of saturation magnetization multiplied by a constant [2].According to our knowledge, this 

law has not been applied on single nanotube. Our results show that although the integral of [µ“ x f ] of single Co nanotube 

is still bounded, but the curve of so-called efficient dynamic magnetization vs. frequency is found having obviously different 

features in comparison with those of magnetic thin films or composites. 

This work is financially supported by National Natural Science Foundation of China (Grant No. 60701016). 

References 

[1] M. Darques, J. Spiegel, J. De la Torre Medina, I. Huynen, and L. Piraux, J. Magn. Magn. Mater. 321, 2055 (2009). 

[2] O.Acher and S. Dubourg, Phys. Rev. B, 77, 10440 (2008). 


79


80 


Poster 

Preparation and properties of silica coated Ni-Fe-Mo flakes composites 

Zo Raolison 1 , Christophe Lefevre 1 , Julien Neige 2 , Anne-Lise Adenot-Engelvin 2 , Geneviève Pourroy 1 , 

Nicolas Vukadinovic 3 

1 IPCMS, UMR 7504 CNRS/Université de Strasbourg, 67034 Strasbourg, France 

2 CEA-DAM Le Ripault, Laboratoire des Matériaux Magnétiques et Optiques, 37260 Monts, France 


Composite magnetic sheets containing ferromagnetic or ferrimagnetic particles are promising candidates for electromagnetic 

(EM) applications such as EM shielding. The microwave properties of such materials are mainly controlled 

by their nature and morphology. It was demonstrated that flaky-shaped particles exhibit improved microwave properties 

in terms of permeability spectra and push away the Snoek’s limit [1]. Eddy-current loss is reduced because 

of the thickness of the particles which is thinner than the skin depth. In addition to the shape effect, an insulating 

layer can be added to prevent electrical conducting path by improving particles dispersion in the matrix and to avoid 

impedance mismatches by lowering its dielectric constants [2]. This communication aims at presenting new developments 

regarding the fabrication of silica coated permalloy flaky particles through the Stöber process and composite 

coatings using the Doctor Blade method [3] and their related microwave properties. Permeability measurements 

carried out using a single coil permeameter [4] connected to a microwave vector network analyzer give access to 

the permeability spectra up to 6 GHz. Permittivity measurements were made using a standard APC-7 coaxial line. As 

compared to composites with uncoated flakes, flaky particles with an insulating layer exhibit lower permittivity levels 

while maintaining the same level of permeability. 

References 

[1] R. M. Walser, W. Win, and P. M. Valanju, IEEE Transactions on Magnetics 34 (4 PART 1), 1390 (1998). 

[2] A. N. Lagarkov and K. N. Rozanov, J. Magn. Magn. Mater. 321, 2082 (2009). 

[3] S. Hallynck, PhD, Elaboration et caractérisations de composites chargés en ferrite spinelle à morphologie contrôlée 

pour utilisations micro-ondes, Université Louis Pasteur de Strasbourg I (2005). 

[4] D.Pain, M. Ledieu, O. Acher, A. L. Adenot, and F. Duverger, J. Appl. Phys. 85, 5151 (1999). 

zo.raolison@ipcms.unistra.fr


Poster 

Large intrinsic microwave permeability and microwave absorption properties of 

Z-type hexaferrites with CoZn substitution 

Mangui Han, Zhenhua Cao, Longjiang Deng 

University of Electronic Science and Technology of China, 610054 Chengdu, China 

Hexaferrites with Z-type structure are believed to have large permeability above 1 GHz due to their special magnetocrystalline 

anisotropy and large natural resonance frequency, and can find applications above 1 GHz, such as the electromagnetic 

noise suppressing. Cation substitution is a frequently adopted method to tune their static magnetic properties and electromagnetic 

properties. In this contribution, hexaferrites Ba (Co Zn ) Fe O (x = 0.2, 0.4, 0.6 and 0.8) samples were prepared 

3 x 1-x 2 24 41 

by traditional two-steps sintering procedures. XRD measurements show that all the samples are in single phase with Z-type 

hexagonal structure. Interestingly, our results show that there are two magnetic loss peaks within 0.5 GHz – 15 GHz for the 

sample with x = 0.2.While there are only one broad magnetic loss peak for other samples.The intrinsic microwave permeability 

have been extracted based on the effective medium theory. Furthermore, the real parts of intrinsic permeability at 1 

GHz have been found to be larger than 7 for all samples. Microwave absorption properties show that sample with x = 0.8 

is the best in terms of reflection loss and bandwidth among these samples.The real parts of permittivity is found increased 

with increasing the Co content. Mössbauer spectra for these samples have been carried out to study the cation distribution 

and the variation of Mössbauer parameters (such as isomer shift, hyperfine magnetic fields, etc) with different x values. 

This work is supported by the Outstanding Young Scholars Foundation of Sichuan Province (No. 2012JQ0053), International 

collaboration project of Sichuan Province (No. 2011HH0001). 


81


82 


Poster 

Normal mode theory for magnonic crystal waveguide 

Natalia Grigoryeva, Boris Kalinikos 

St.Petersburg Electrotechnical University, 197376 St.Petersburg, Russia 

Propagating spin waves in various magnetic nanostructures and particularly in magnonic crystals nowadays attract 

a considerable attention due to their potential application as information carriers in integrated signal processing 

devices [1-5]. In presented work a general theory of the dipole-exchange spin-wave spectrum of magnonic crystal 

waveguide has been developed. Magnonic crystal waveguide is assumed to be a thin-film ferromagnetic waveguiding 

medium with periodical modulation of the magnetic parameters along the spin-wave propagation direction. The 

periodical variation the magnetic parameters is taken into account in the frames of the Floquet theorem for differential 

equation with periodic coefficients.The spin-wave modes approach together with the method of tensorial Green’s 

functions is used to describe the spectrum of propagating spin waves. The exact dispersion relation is obtained 

in the form of an infinite determinant, which can be easily reduced to the finite one for each particular problem under 

consideration. As an example of the success theory application the numerical calculations of spin-wave spectrum 

for the dynamic magnonic crystal are presented. The calculated spectrum is compared with experimental results for 

YIG based dynamic magnonic crystal waveguide from [6]. 

References 

[1] S.A. Nikitov, Ph. Tailhades, C.S. Tsai, J. Magn. Magn. Mater. 236, 320 (2001). 

[2] H. Puszkarski, M. Krawczyk, Sol. St. Phenom. 94, 125 (2003). 

[3] V.E. Demidov, S.O. Demokritov, K. Rott, et al., J. Phys. D: Appl. Phys. 41, 164012 (2008). 

[4] N.Yu. Grigorieva, B.A. Kalinikos, M.P. Kostylev, A.A. Stashkevich. In Handbook of Artificial Materials, Vol. I: 

Theory and Phenomena of Artificial Materials, ed . by F. Capolino pp. 34-1-68. Taylor and Francis Group, LLC., 

Oxford, UK (2009) 

[5] A.A. Serga, A.V. Chumak, B. Hillebrands, J. Phys. D: Appl. Phys. 43, 264002 (2010). 

[6] A.V. Chumak, T. Neumann, A.A. Serga, et al., J. Phys. D: Appl. Phys. 42, 205005 (2009). 

natalygri69@gmail.com


Poster 

FMR and magnetic studies on polycrystalline YIG thin films deposited using pulsed 

laser 

Biswanath Bhoi 1 , N. Venkataramani 2 , R.P.R.C. Aiyar 1 , Shiva Prasad 3 

1 Center for Research in Nanotechnology and Science, Indian Institute of Technology Bombay, 400076 Mumbai, India 

2 Department of Metallurgical and Material Science, Indian Institute of Technology Bombay, 400076 Mumbai, India 

3 Department of Physics, Indian Institute of Technology Bombay, 400076 Mumbai, India 

Epitaxial Yttrium iron garnet (Y Fe O or YIG) films have been of interest due to its narrow line width essential for 

3 5 12 

microwave application. Liquid-phase epitaxy (LPE) and pulsed laser deposition (PLD) are well-established methods for 

fabrication of epitaxial YIG films with low line-width (∼1 Oe) and high saturation magnetization (∼bulk YIG) [1]. In this 

paper we report the growth of polycrystallineYIG films on quartz substrate using PLD and investigate its magnetic and 

microwave properties. 

Thin film depositions have been carriedout in oxygen atmosphere (5×10 –2 mbar) using a range of laser energy (240 mJ to 

350 mJ) on quartz substrates at a temperatureof 750 °C.The films were then ex-situ annealed (T ) at 700 °C in air for 2 hrs. 

a 

The effect of laser energy on the thickness, crystalline quality and magnetic properties of YIG thin films has been studied. 

The film thickness increases from 100 nm to 290 nm for an hour deposition with the increase in laser energy from 240 mJ 

to 350 mJ.The FMR line-width, on the other hand, reduces from 340 Oe to 70 Oe for the same incremental variation in laser 

energy. Multiple resonance modes have been observed in the perpendicular FMR spectra of our samples which is related 

to intrinsic as well as extrinsic mechanisms such as inhomogeneities [2]. Saturation magnetization measurement (M s ) has 

been performed using physical property measurement system (PPMS) and is found to be dependent on the film thickness. 

The value of M is found to increase with the thickness and is close to 90 percent of the bulk value for the film with highest 

s 

thickness. In this paper an attempt has been made to correlate the magnetization results with FMR and eventually with 

microstructure. 

References 

[1] V. G. Harris,et al., J. Magn. Magn.Mater. 321, 2035 (2009). 

[2] J. Dash, S Prasad, N.Venkataramani, R. Krishnan, P. Kishan, N. Kumar, S. D. Kulkarni, and S. K. Date, J.Appl. Phys. 86, 

3303 (1999). 

bhoi.biswanath@gmail.com 

83


84 


Poster 

The phonon-magnonic bandgaps in 1D magnonic crystals based on surface 

corrugated YIG 

Aleksandra Trzaskowska 

Faculty of Physics,Adam Mickiewicz University, 61-614 Poznaρ, Poland 

The properties of magnetoelastic waves (MEW) which are a result of coupling between magnetostatic surface 

waves (MSSW) and elastic volume shear waves in 1D magnonic crystal (MC) based on Ga, Sc-substituted YIG/GGG 

(Ga,Sc:YIG) epitaxial structure were studied. MC was prepared by photolithography and etching as the structure of 

stripes 80 mm in width, 0.25 mm in depth, period L = 150 mm on the surface of 2.2 mm thickness of Ga, Sc: YIG with 

magnetization 750 Gs epitaxially growth on 500 mm GGG substrate. In tangential bias field H ∼ 0.05÷0.1 kOe oriented 

along the stripes and perpendicular to MSSW wave vector k we attributed interaction between MSSW and shear 

elastic volume waves of Ga,Sc:YIG/GGG elastic waveguide. This interaction produced a Δf = 3.57×10 6 Hz oscillation 

in transmitted MSSW characteristic. At frequency correspondent to MSSW (and shear waves) Bragg resonance at 

k B = πN /Λ (N = 1, 2...) we observed formation of the forbidden frequency gaps. These forbidden gaps are treated 

as a magnonic and phononic gaps on MSSW and elastic shear waves. 

The experimental results are supported by the dispersion relation for shear volume elastic waves propagating in the 

YIG/GGG studied and MSSW propagating in the 1D MC calculated with the finite elements method.


Poster 

Synthesis and properties of magnetic nanoparticles for high frequency materials 

Zuzana Kozakova, Ivo Kuritka, Vladimir Babayan 

Tomas Bata University in Zlin, 760 01 Zlín, Chech Republic 

Nowadays, magnetic materials are intensively studied in the nanoscale due to their possible advanced applications in 

electronics, medicine and pharmacy. Soft magnetic and ferromagnetic materials are proper candidates for the use in micro- 

wave applications, such as microwave absorbers, filters or antenna cores. Tailoring the properties for the best performance 

in the required function can be challenging in the nanoscale, therefore, it is crucial to understand the mechanisms of the 

nanoparticles formation in the connection with their structure and magnetic behavior. For this purpose, a conventional 

solvothermal process was modified by the use of microwave pressurized reactor. The efficiency and therefore prospective 

economical and environmental impact was enhanced by the direct heating of reacting material and non thermal effects 

within the microwave-assisted synthesis. Structure, morphology and particle size were modified by the change of 

synthetic parameters in order to tailor the magnetic properties of prepared magnetite nanoparticles. The nature of obtained 

product can be changed from ferromagnetic to superparamagnetic by gentle variation of reaction conditions. Both, static 

and dynamic magnetic characterization of prepared materials confirmed achievement of controllability over large range 

of parameters as saturation magnetization, coercivity and complex magnetic permeability. 

zkozakova@ft.utb.cz 

85


86 


Poster 

Induced giant magnetoimpedance effect by current annealing in ultra thin Co-based 

amorphous ribbons 

Julián González 1 , Mihail Ipatov 1 , Lorena González 2 , Javier Garcia 2 , Alexander Chizhik 1 , Lourdes Dominguez 3 , 

Valentina Zhukova 1 , Arkady Zhukov 1 , Blanca Hernando 2 

1 Department Materials Physics, Faculty of Chemistry, University of the Basque Country, 20018 San Sebastián, Spain 

2 Department Physics, Faculty of Sciences, University of Oviedo, 33007 Oviedo, Spain 

3 Department Applied Physics I, EUPDSS, University of the Basque Country, 20018 San Sebastián, Spain 

The giant magnetoimpedance effect (GMI) has been an intensively research activity owing to the promising and, even, 

real technological applications. Such scientific research has dealt several aspects concerning the intrinsic magnetotransport 

properties (i.e.: frequency range, intensity of the effect, magnetic field to observe possible maximum, noise,…) 

as well as those related with microstructural (mainly amorphous or nanocrystalline) or geometrical character 

(initially wire, but GMI has been reported in glass-coated microwire, ribbon, thin film) and, therefore, GMI is actually 

opening a new branch of research combining the micromagnetics of soft magnets with the classical electrodynamics. 

Obviously, the different geometry lead to some differences in the GMI response like the range of frequency or the 

magnetic field dependence of the impedance curve with one or two peaks or, it could be relevant the shape of the 

peak, etc. 

Amorphous ribbon of nominal composition (Co Fe ) Si B fabricated by melt-spinning technique (0.50 mm 

0.95 0.05 75 10 15 

wide, 32 mm thick and pieces of 8 and 20 mm length) were investigated. These pieces were submitted to current 

annealing (440-680 mA, 5 minutes), which develops a transverse magnetic anisotropy of average value of around 

100 J/m3 , although of inhomogeneous character, that enhances the mentioned circular susceptibility. The impedance 

of as-cast and current annealed pieces was measured with a vector network analyzer in rejection mode 

(0.01-2.0 GHz) and an external magnetic field up to 15 kA/m applied along the longitudinal direction of the ribbon. 

Two-peaks behaviour in GMI effect is observed in all current annealed ribbons. The effect is enhanced as increasing 

the intensity of the current annealing (560 mA results to be maximum the effect) as well as monotonously with the 

frequency. This behaviour is explained in terms of the skin depth penetration and the dispersion of easy axes along 

the ribbon thickness. 

julianmaria.gonzalez@ehu.es


Poster 

Dielectric and AC-magnetic response of the complex spin ordering processes 

in Mn 3 O 4 

Subhash Thota 1 , Kiran Singh 2 , Charls Simon 2 , Wilfrid Prelier 2 

1 Indian Institute of Technology Guwahati, 781039 Guwahati, India 

2 Laboratoire CRISMAT, CNRS UMR 6508, ENSICAEN, 14050 Caen, France 

We report a meticulous study of the magnetization dynamics and dielectric response of various complex magnetic transitions 

take place in the temperature range 30 – 45 K in Mn O . For the first time we observed a clear hysteresis of about 

3 4 

5.15 K in the dielectric permittivity (ε‘) across the incommensurate-to-commensurate transition at 34 K which supports the 

general predictions of a first order transition. This anomaly in ε‘ at 34 K is independent of applied dc-magnetic field (H DC ) 

even at 14 kOe. On the other hand, the relative dielectric constant ([ε‘(T ) -ε‘(8 K)] / ε‘(8 K)) exhibits a step change across the 

ferrimagnetic Néel temperature (T ~ 42.75 K) which is highly sensitive to H . Such a correlated giant dielectric anomaly 

N DC 

across T completely disappears when H ≥ 10 kOe. These results are supported by the temperature dependent speci- 

N DC 

fic heat capacity C (T ) and ac-magnetic susceptibility χ (T ) measurements. Irreversible magneto-dielectric curves (ε‘/ε‘ 

p AC 

vs.H) were observed below Yafet-Kittel ordering with a negative shift across the spiral incommensurate phase. Besides the 

known sequence of complex magnetic transitions at T N ~ 42.75 K, T 1 ~ 39 K, and T 2 ~ 34 K, a new anomaly close to 38 K 

(T*) is observed in both M (T ) and C p (T ) results, which is successfully probed by using the χ AC (T ), and ε‘(H DC ) measurements. 

The χ AC (T ) plots at different frequency intervals between 1 Hz – 1000 Hz were used to study the dynamic behavior of all 

the transitions. Consequently, χ AC exhibits a strong cusp at T* which is extremely susceptible to the frequency of 

ac-magnetic signal and dc-probing field. Such small features occurring below T N also show their signatures in the 

magnetic entropy change. All the transitions observed in magnetic and dielectric measurements have been interpreted 

in consonance with the C p (T ) data. 

subhasht@iitg.ac.in 

87


88 

Magnetization dynamics and Relaxation P11 

Poster 

Ferromagnetic resonance of a magnetic nanostripe array using a micron-sized 

coplanar probe 

Crosby Chang 1 , Mikhail Kostylev 1 , Adekunle Adeyeye 2 , Matthieu Bailleul 3 , Sergey Samarin 1 

1 University of Western Australia, 6009 Crawley,Australia 

2 National University of Singapore, 117576 Singapore, Singapore 

3 IPCMS CNRS/Université de Strasbourg, 67034 Strasbourg, France 

Magnetic nano-stripes (MNS) show promising technological applications as microwave filters, delay lines, and magnetic 

memory storage. One way to characterise the dynamic magnetic properties of magnetic materials is using 

ferromagnetic resonance (FMR). The standing spin wave modes (SSWMs) in thin magnetic films and nanostructures 

provide important information about the exchange interaction and magnetic conditions at surfaces and buried interfaces. 

Often, SSWMs with odd symmetry are lacking in FMR spectra for symmetry reasons [1]. 

The objects studied are periodic arrays of Permalloy (Ni Fe ) stripes patterned using deep-ultraviolet lithography [2]. 

80 20 

Each stripe is 100 nm thick, 264 nm wide and 4 mm long with stripe edge-to-edge spacing of 150 nm. We performed 

FMR measurements on this MNS using a new method: by direct injection of microwave currents into the MNS using 

a sub-milimetre microwave coplanar probe [3]. The probe has a ground-signal-ground tip width of 400 microns and 

contacts the MNS such that microwave current flows from the signal tip to the ground tips through the MNS. External 

magnetic field is applied parallel to the stripes. 

We show that in contrast with the traditional microstrip method, our coplanar probe method is able to efficiently 

excite SSWMs with odd symmetry in the MNS. We propose this is due to confinement of real microwave currents 

along the nano-stripes which induce a non-uniform microwave magnetic field, and which in turn, couples efficiently 

with SSWMs with odd symmetry. The proposed method is quick and also allows easy spatial mapping of magnetic 

properties with resolution down to 100 microns, which is the tip size of the smallest commercially available probe. 

References 

[1] C. Kittel, Phys Rev. 110, 1295 (1958). 

[2] A. O. Adeyeye and N. Singh, J Phys. D Appl. Phys. 41, 153001 (2008). 

[3] C. S. Chang et al., Europhys. Lett. 96, 57007 (2011). 

crosby.chang@uwa.edu.au


Poster 

Nonlocal feedback in ferromagnetic resonance 

Thomas Bose, Steffen Trimper 

Martin-Luther-University Halle,Theoretical Physics Department, 06120 Halle, Germany 

Ferromagnetic resonance in thin films is analyzed under the influence of spatiotemporal feedback effects. The equation 

of motion for the magnetization dynamics is nonlocal in both space and time and includes isotropic, anisotropic and dipolar 

energy contributions as well as the conserved Gilbert- and the non-conserved Bloch-damping. From this we derive 

an analytical expression for the peak-to-peak linewidth. It consists of four separate parts originated by Gilbert damping, 

Bloch-damping, a mixed Gilbert-Bloch component and a contribution arising from retardation. In an intermediate frequency 

regime the results are comparable with the commonly used Landau-Lifshitz-Gilbert theory combined with two-magnon processes. 

Retardation effects together with Gilbert damping lead to a linewidth the frequency dependence of which becomes 

strongly nonlinear. The relevance and the applicability of our approach to ferromagnetic resonance experiments is discussed. 

thomas.bose@physik.uni-halle.de 

89


90 


Poster 

Thermodynamic and relaxation processes in phase transitions in advanced magnetocaloric 

materials 

Alexander Kamantsev, Victor Koledov, Vladimir Shavrov 

Kotelnikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, 125009 Moscow, Russia 

The research in the field of the new technology of refrigeration at room temperature based on magnetic materials 

with phase transitions (PT) attracts much attention last years. In spite of the fact that magnetic PT were investigated 

theoretically and experimentally for a long time, at the moment there is no deep understanding of the kinetic phenomena 

occurring with magnetic PT, which is crucial in development of this technology. It is very important to know the 

fundamental physical restrictions on speed of relaxation processes of order parameter (magnetization) near critical 

point of PT. Theoretically [1], relaxation processes near the 2d order PT point are described by Landau-Khalatnikov 

equation: dη / dt = -γ(∂Ω /∂η), where η – order parameter, t – time, Ω – thermodynamic potential, γ – kinetic coefficient. 

The aims of present work were the following: 

1) Theoretical study of heat exchange processes between the water coolant and the plate made of magnetocaloric 

material in order to estimate the time response of heating and cooling. 

2) To develop the experimental method for the measurement of the time of establishment of the equilibrium value of 

order parameter after fast heating and cooling of the sample in the form of thin plate near PT critical temperature. 

3) To estimate achievable magnitude of power-to-weight ratio of magnetocaloric refrigerator or thermal pump with 

working made of different magnetic materials. 

References 

[1] L.D Landau and I.M. Khalatnikov, Doklady Akademii Nauk USSR 96, 469 (1954). 

kama@cplire.ru


Poster 

Standing spin waves in 1D Co/Py magnonic crystals 

Michal Mruczkiewicz 1 , Maciej Krawczyk 1 , Valentine K. Sakharov 2 , Yuri V. Khivintsev 2 , Yuri Filimonov 2 , 

Sergei A. Nikitov 2 

1 Adam Mickiewicz University, 61-712 Poznan, Poland 

2 Kotel‘nikov IRE RAS, 410019 Saratov, Russia 

Localized modes of magnetostatic waves have been observed experimentally and investigated numerically in periodic 

Co/Py magnonic crystals (MCs) and in arrays of separate stripes of Py. The MCs were fabricated using magnetron sputtering, 

photolithography and ion etching to form 50 nm thick alternating Co and Py stripes of 6.6 and 3.4 µm width. We used 

single lithography process and applied the same photoresist pattern for ion etching of the Co film and lift-off method for 

the Py film. The Landau-Lifshitz equation has been solved for monochromatic spin waves using the finite element method. 

We have obtained the set of eigenvalues (resonance fields) at defined frequency and corresponding spatial dependence 

of dynamic magnetization components. The overlapping integral of the external electromagnetic field and the spin wave 

amplitude was executed in order to calculate the relative intensity of absorption, the FMR spectra. We have found agreement 

between numerical calculations and FMR experimental data for Damon-Eshbach (DE) and Backward Volume (BV) 

geometry. Because of significantly different magnetizations Co and Py have different values of uniform resonant fields 

(H 0,Py and H 0,Co ) at fixed frequency. In the field region δH: H 0,Py ≤ δH ≤ H 0,Co for DE geometry a resonance for spin waves 

is possible only in Py regions of MC. In contrary for BV geometry spin waves propagation is allowed only in Co regions. 

The reflection conditions on element boundaries led to standing spin waves formation in Py elements for DE geometry and 

in Co stripes for BV geometry while for arrays of separate Py stripes with the same dimensions localized modes are formed 

in both geometries. Experimentally we observed only modes localized in Py regions of MC but no response from modes in 

Co elements in BV configuration. It is due to the fact that Co stripes have rather big width and low value of the propagation 

length to fulfill the condition of forming the standing waves. 

m.mru@hotmail.co.uk 

91


92 


Poster 

Spin wave dispersion in striped magnonic waveguide 

Nikhil Kumar, Anil Prabhakar 

Indian Institute of Technology Madras, 600036 Chennai, India 

The spin wave spectra of magnonic devices with alternating materials in space have been studied experimentally and 

analytically [1, 2]. The basic advantage of such devices is that the frequency and width of the band gap is tunable 

by an applied field, or modified by the material properties. The structure under the investigation has the form of thin 

strips of permalloy and cobalt alternately arranged as a planar waveguide. The structure is assumed to be infinite in 

length and finite in thickness and width. Spin wave propagation is assumed along the length of the stripe, parallel to 

the external applied field, in a backward volume configuration. 

We derive both static and dynamic fields in the magnonic waveguide using the plane wave method, which uses 

a Bloch wave expansion to account for the spatial periodicity [3]. The linearized Landau-Lifshitz equation, in the 

frequency domain, was reduced to an eigenvalue problem. The obtained eigenvalues are tested for convergence, 

and we obtain satisfactory numerical convergence when we use 20 reciprocal lattice vectors. The eigenfrequencies 

corresponding to a wave vector are then numerically calculated and plotted. Finally, the eigenmode for a specified 

wave vector and frequency yields the spatial variation in spin wave amplitudes. 

The demagnetizing field, directed along length and thickness, was derived from the magnetostatic potential and 

shows both bulk and edge mode characteristics. In a non-uniform demagnetizing field, low frequency spin waves 

concentrate their amplitude in a region of low internal magnetic field. These appear as standing wave excitations in 

the permalloy resulting in zero group velocity, or a flat band structure in the ω (k ) in the dispersion diagram. 

Finally the dependence of the angle between propagation spin wave vector and applied field is investigated by changing 

the angle between the applied field and wave vector. This non-zero angle, due to a quantized wave vector along 

the width, removes the flat band structure and we again see band gaps in ω (k ). 

References 

[1] Z. K. Wang, V. L. Zhang, H. S. Lim, S. C. Ng, M. H. Kuok, S. Jain, and A. O. Adeyeye, ACS Nano 4, 643 (2010). 

[2] M. Sokolovskyy and M. Krawczyk, J. Nano. Res. 13, 6085 (2011). 

[3] M. Krawczyk and H. Puszkarski, Phys. Rev. B 77, 054437 (2008). 

nikhilkumarcs@gmail.com


Poster 

Nondiffractive origin of bandgaps in periodic lattices 


Instituto Superior Tecnico, 1049-001 Lisbon, Portugal 

It is assumed generally that the bands forbidden for wave propagation (bandgaps) at the Brillouin zone (BZ) edges in 

engineered periodic systems [artificial crystals (AC´s)] occur due to backward Bragg diffraction. We propose another 

mechanism that induces the bandgap formation in AC’s. This mechanism is studied in the near-field configuration 

where waves are excited inside an AC. In this case the bandgaps occur at the BZ edges as well; though the me- 

chanism for their formation is essentially different from that associated with Bragg diffraction. The mechanism is 

illustrated with a thin-film ferromagnetic medium where the saturation magnetization, Ms, is periodically modulated 

in one of lateral directions. In such a hypothetical lattice, we emphasize the occurrence of the two dominating spin– 

wave modes that can be referred to as ordinary (O) and extraordinary (EO) waves by analogy with the phenomenon 

of birefringence taking place in anisotropic materials. The O mode is identical (outside the bandgaps) to that excited 

in a homogeneous medium where Ms is constant through space. These two modes travel through the lattice in the 

same direction but the EO mode has negative group velocity and dispersion, which are opposite to those quantities 

in the O mode. As result, the O and EO modes encounter each other and their intersection occurs at a BZ edge where 

they interfere destructively. As the O and EO wave packets show dispersions of opposite polarity, their superposition 

provides a nonzero dispersion at the wave vector for which the spin-wave intensity is maximal. This means that the 

superposition of the O and EO modes breaks the necessary condition for ferromagnetic resonance and no effective 

excitation of the magnetic oscillations occurs in the lattice at BZ edges. 

Work was supported by the Portuguese Foundation for Science and Technology via research grant PTDC/ 

FIS/121588/2010. 

nipolushkin@fc.ul.pt 

93


94 


Poster 

Magnetization dynamics of Co antidot lattices 

Andreas Neudert 1 , Rantej Bali 1 , Mikhail Kostylev 2 , Adekunle Adeyeye 3 , Florian M. Römer 4 , Kai Wagner 4 , 

Michael Farle 4 , Kilian Lenz 1 , Jürgen Lindner 1 , Jürgen Fassbender 1 



3 National University of Singapore, 117576 Singapore, Singapore 

4 Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CeNIDE), Universität Duisburg-Essen, 47048 Duisburg, 

Germany 

We have systematically investigated the static and dynamic magnetic properties of Co(t nm)/CoO(5 nm)/Cu(2 nm) 

antidot lattices forming square patterns as a function of Co thickness and hole diameter.The antidots were fabricated 

using large-area patterning and photo-lithography [1]. The Co film thicknesses, t , were varied between 25 and 100 

nm, into which holes were patterned in the form of square lattices with fixed lattice spacing (centre to centre distance 

between the holes) of 415 nm along the direction.The hole diameter was varied and 145, 185, 225 and 265 nm 

holes were fabricated for each film thickness. 

The quasistatic magnetic properties were measured using in-plane magneto-optical Kerr effect (MOKE) magnetometry. 

The angular dependence of saturation fields (Hs) shows minima along the directions suggesting 4-fold 

anisotropy. Local minima in Hs are observed along suggesting a quasi-8-fold effect. Angular dependence of the 

FMR spectra measured in a cavity at the X-band shows easy axis behavior along the and hard axis behavior 

along the . 

Frequency dependent FMR spectra were measured along the and directions. An intriguing ‘frequency 

gap’ around 6 GHz and 0.1 T is observed in the dispersions measured along the directions. As the frequency 

approached 6 GHz, the fundamental mode splits into two modes of nearly equal intensity and the higher field mode 

dominates with further increase in frequency. This feature is strongest on Co antidot arrays with t = 50 nm thickness 

and d = 145 nm, but is also observed on some samples of larger t and d. 

Micromagnetic simulations will be performed to correlate the frequency gaps to possible rearrangement of the circumferential 

spins around 0.1 T. The dynamics of the Co-antidots averaged over large areas as measured using 

FMR spectroscopy will be compared with the localized, near surface dynamic measurements using Time Resolved 

Magneto-optic Kerr effect (TR-MOKE) with an optical pump-probe scheme. 

References 

[1] C. C. Wang et al. 2006 Nanotechnology 17, 1629 (2006). 

a.neudert@hzdr.de


Poster 

Control of spin-wave phase and wavelength in microscopic magnonic waveguides 

Vladislav Demidov 1 , Sergej Demokritov 1 , Mikhail Kostylev 2 

1 University of Muenster, 48149 Münster, Germany 


Recently a concept of integrated signal- and data-processing based on propagation of spin waves in microscopic 

magnetic-film waveguides has been elaborated. One of the most significant challenges for further development in 

the field is the realization of efficient excitation of spin waves in micro-waveguides, as well as finding mechanisms for 

efficient spin-wave manipulation on the microscopic scale. 

Here we experimentally demonstrate the ability to control the characteristics of spin waves propagating in submicrometer 

magnonic waveguides by electric current. By using phase-resolved micro-focus Brillouin light scattering 

spectroscopy, we directly measured the wavelength and the phase of spin waves propagating in Permalloy waveguides 

deposited on top of control lines. Our results show that in such geometry the wavelength of spin waves can be 

changed by nearly a factor of two, and their phase can be varied by more than ±π radians over the length of several 

micrometers, by utilizing a dc current as small as ±12 mA. We also demonstrate a phenomenon of the wavelength 

conversion in micro-waveguides with spatially varying cross-section. We show that using this approach, the wavelength 

of spin waves can be reduced by more than a factor of 10 over a propagation distance of 2-5 micrometers 

enabling efficient excitation of spin waves with sub-micrometer wavelengths by standard inductive techniques. We 

show that in the studied waveguides the wavelength conversion is accompanied by only moderate conversion losses, 

which makes the phenomenon promising for technical applications. 

References 

V. E. Demidov, J. Jersch, S.O. Demokritov, K. Rott, P. Krzysteczko, and G. Reiss, Phys. Rev. B 79, 054417 (2009). V. E. 

Demidov, S. Urazhdin, and S. O. Demokritov, Appl. Phys. Lett. 95, 262509 (2009). V. E. Demidov, M. P. Kostylev, K. Rott, 

J. Münchenberger, G. Reiss, and S. O. Demokritov, Appl. Phys. Lett. 99, 082507 (2011). 

demidov@uni-muenster.de 

95


96 


Poster 

Storage-recovery phenomenon in a magnonic crystal 

Andrii Chumak 1 , Vitaliy Vasyuchka 1 , Alexander Serga 1 , Mikhail Kostylev 2 , Vasyl Tiberkevich 3 , Burkard Hillebrands 1 

1 Fachbereich Physik and Forschungszentrum OPTIMAS,Technische Universität Kaiserslautern, 67663 Kaiserslautern, 

Germany 

2 School of Physics, University of Western Australia, Crawley,Western Australia 6009,Australia 


The deceleration or even the full stop of light due to the modification of the light dispersion in photonic crystals 

has been a topic of intense studies over the last decade. A wave of light propagating through a PC couples with the 

internal standing crystal mode and generates a slow light mode which can be used for storage of optical signals [1]. 

Magnonic crystals (MCs) are the magnetic counterpart of photonic crystals which operate with spin waves. The wide 

range of MCs parameters which can be tuned as well as the possibility of fast dynamic control of these parameters 

[2] make MCs promising candidates for the fundamental studies and processing of information in the GHz frequency 

range. However, in spite of the progress in MCs studies, neither spin-wave deceleration nor storage-recovery of a 

spin-wave carried signal has been demonstrated yet. This is due to significant spin-wave damping which limits the 

maximum number of structure periods to 20 or so. The small number of periods implies that the group velocity of spin 

waves rather than vanishing only slightly decreases about 20 percent at the gap edges. This makes the realization of 

storing a signal in a MC using the slow spin-wave mode questionable. 

As an alternative solution, in this paper we show experimentally that the storage-recovery phenomenon can be 

successfully realized in magnonic crystal with a limited number of periods by the use of a quasi-normal mode (QNM) 

of this structure [3]. This mode is excited by the incident travelling spin wave and conserves oscillation energy for a 

long time after the propagating wave has left the MC area. Upon subsequent parametric amplification the internal 

mode irradiates part of its energy back into the propagating spin wave allowing the coherent restoration of the stored 

signal. The restoration occurs near the edges of the MC band gaps in narrow (1.2 MHz) frequency windows around 

QNM eigen-frequencies, which coincide with the local minima of the spin-wave group velocity.The dependence of the 

restored signal power on the phase of the input wave evidences simultaneous amplification of two phase-coupled 

waves of opposite wavevectors, and thus corroborates the role of the standing MC mode in the storage mechanism 

[3]. The results presented here provide deeper understanding of the storage-recovery mechanisms in periodic lattices 

in general. Besides, they suggest a potential possibility of utilization of magnonic crystals for buffering or storage of 

microwave information. 

References 

[1] T. Baba, Nat. Photon. 2, 465 (2008). 

[2] A.V. Chumak, V. S. Tiberkevich, A. D. Karenowska, A. A. Serga, J. F. Gregg, A. N. Slavin, and B. Hillebrands, Nature 

Commun. 1:141, doi: 10.1038/ncomms1142 (2010). 

[3] A. V. Chumak, V. I. Vasyuchka, A. A. Serga, M. P. Kostylev, and B. Hillebrands, Phys. Rev. Lett. 108, 257207 (2012). 

chumak@physik.uni-kl.de


Poster 

Ab-initio calculation of the Gilbert damping parameter via linear response formalism 

Sergeiy Mankovskyy, Hubert Ebert, Diemo Koedderitzsch 

University of Munich, 81377 München, Germany 

A Kubo-Greenwood-like equation for the Gilbert damping parameter is presented that is based on the linear respon- 

se formalism. Its implementation using the fully relativistic Korringa-Kohn-Rostoker (KKR) band structure method 

in combination with Coherent Potential Approximation (CPA) alloy theory allows it to be applied to a wide range 

of situations. This is demonstrated with results obtained for various transition metal systems including disordered 

alloys. To account for the thermal displacements of atoms as a scattering mechanism, an alloy-analogy model 

is introduced. Corresponding results for the pure ferromagnetic metals Fe, Co and Ni as well as some alloy systems 

will be presented. The same scheme can be applied to account for the influence of spin fluctuations as will 

be demonstrated by first applications. 

Hubert.Ebert@cup.uni-muenchen.de 

97


98 


Poster 

Shielding of the electromagnetic field of a coplanar waveguide by a metal film: implications 

for broadband ferromagnetic resonance measurements 


IPCMS CNRS/Université de Strasbourg, 67034 Strasbourg, France 

Most of spintronics devices rely on thin ferromagnetic metal films (Fe, Co, Ni and their alloys). Because these devices 

are to be operated often in the high frequency (GHz) regime, it is essential to characterize precisely the microwave 

magnetic response of these films. For this purpose, broadband techniques have been developed in the last ten years. 

In the simplest implementation, the ferromagnetic film is placed directly above a broadband transmission line such 

as a coplanar waveguide (CPW). The magnetic response -namely the ferromagnetic resonance (FMR)- is extracted 

from the change of the inductance of the loaded transmission line (so-called flip-chip FMR, CPW-FMR or NA-FMR 

techniques). Although the technique is relatively straightforward to implement, the extraction of the magnetic parameters 

from the measured microwave signal raises a number of difficulties. In particular, Kostylev has shown recently 

that most of the metal films investigated are conducting enough to modify strongly the microwave propagation mode 

of the transmission line.[1] This modification was described in terms of shielding: Eddy currents flowing into the film 

are able to shield completely the electromagnetic field delivered by the transmission line. Surprisingly, this happens 

even for film thickness much smaller than the microwave skin depth. Interestingly, this phenomenon has essential 

consequences for ferromagnetic resonance measurements: In the case of shielding, the microwave magnetic field 

becomes inhomogeneous enough to couple to perpendicular standing spin wave modes which could not be accessed 

in the unshielded situation. 

In this communication, I report on a detailed description of the phenomenon of shielding in a realistic geometry. For 

this purpose, a full wave 2D electromagnetic simulation is first carried out. This indicates that the metal film is able to 

shield completely the electric and/or the magnetic field of the coplanar waveguide according to the value of its square 

resistance. These results are then interpreted quantitatively with the help of a simple distributed impedance model 

accounting for the shielding currents likely to flow along the metal film. This model allows one to predict the range of 

parameters for which shielding of the electric and/or magnetic fields is expected to occur. Preliminary measurements 

indicating the excitation of perpendicular standing spin wave modes will also be analyzed with the help of this model. 

From this communication it will be concluded that the phenomenon of shielding should be accounted for in most of 

the broadband inductive measurements of ferromagnetic resonance performed on metal ferromagnetic films. 

References 

[1] M. Kostylev, J. Appl. Phys. 106, 043903 (2009). 

bailleul@ipcms.u-strasbg.fr


Poster 

Mode selective parametric excitation of spin waves in a Ni 81 Fe 19 microstripe 

Thomas Brächer, Philipp Pirro, Björn Obry, Alexander Serga, Britta Leven, Burkard Hillebrands 

Fachbereich Physik and Forschungszentrum OPTIMAS,Technische Universitaet Kaiserslautern, 67663 Kaiserslautern, 

Germany 

Due to their potential application in logic devices and microwave signal processing spin-wave excitations have been 

intensively studied. However, experiments in microstructured systems remain a challenge since the spin-wave life- 

time in commonly used materials like Permalloy (Ni 81 Fe 19 ) is restricted to a few nanoseconds. A possible approach 

to address this issue is the prolongation of the spin-wave lifetime by using the technique of parallel parametric 

amplification [1]. 

We present the experimental observation of parallel parametric amplification of selected thermal spin-wave modes 

in a transversally magnetized Ni 81 Fe 19 microstripe [2], investigating the nature of the amplified modes. 

By employing Brillouin light scattering microscopy we identify the dominant group, i.e. the spin-wave mode that 

is preferentially amplified. We show that due to the existing spin-wave quantization in the system it is possible 

to select one specific mode to be parametrically excited by changing the bias magnetic field. This gives access to 

transversal spin-wave eigenmodes of the stripe, promising the ability to amplify externally excited propagating spin 

waves that carry information, and also allows for the generation of modes localized at the stripe edges. We explain 

the mode-selectivity by the wave-vector dependent ellipticity of precession in a thin magnetic stripe. 

References 

[1] V. S. L’vov, Wave Turbulence under Parametric Excitations: Applications to Magnetics, Springer, Berlin (1994). 

[2] T. Brächer et. al., Appl. Phys. Lett. 99, 162501 (2011). 

braecher@rhrk.uni-kl.de 

99



Poster 

Scanning probe ferromagnetic resonance imaging of stripe patterned exchange bias 

film 

100 

Rohan Adur 1 , Inhee Lee 1 , Yuri Obukhov 1 , Christine Hamann 2 , Jeffrey McCord 2 , Denis V. Pelekhov 1 , P. Chris Hammel 1 

1 Ohio State University, 43210 Columbus, USA 

2 IFW Dresden, D-01069 Dresden, Germany 

Ferromagnetic Resonance Force Microscopy (FMRFM) is a technique that can be used for imaging inhomogeneities 

at interfaces and in buried structures by localizing a magnetostatic mode in the strong magnetic field of a micromagnetic 

probe. An antiferromagnet can be used to apply an effective exchange bias field when in contact with an 

adjacent ferromagnet. Here, we use FMRFM imaging to map the spatial variation in internal field when the exchange 

bias direction has been reversed in stripe regions by He-ion implantation. We measure the exchange bias field and 

demagnetizing field for the as-deposited and ion-implanted regions.The FMR mode can be localized by the boundary, 

and an approximation of a Bessel mode confined by the probe field and the field step at the boundary of a stripe 

is effective in describing the observed field shifts when the probe is scanned across the stripe boundary. 

adur.2@osu.edu


Poster 

Spin dynamics excitation in nonlocal spin-valves 

Milan Agrawal 1 , Hiroshi Idzuchi 2 , Yasuhiro Fukuma 2 , Alexander Serga 1 , Yoshichika Otani 3 Burkard Hillebrands 1 


Germany 

2 ASI and RIKEN, University of Tokyo, 277-8581 Kashiwa, Japan 

3 University of Tokyo, 277-8581 Kashiwa, Japan 

Spin injection, excitation and detection in non-magnetic materials are the key techniques for the development of 

spintronics industry. The manipulation of injected spin current inside a nonmagnetic metal is of great importance from 

the application perspective. Here we report on the influence of radio frequency (RF) magnetic field on the spin current 

injected in nonlocal spin-valve composed of Permalloy (Py) and Silver (Ag). Spin devices are comprised of a typical 

nonlocal spin-valve geometry placed in the vicinity of a microwave antenna fabricated on the same substrate. Spin 

polarized electrons from a magnetized ferromagnetic injector of Py are inserted in the silver channel to create a pure 

spin current there which afterward interacts with the microwave magnetic field while flowing through the channel 

and detected by the second Py wire placed on the other end of Ag channel. Experimental findings reveal that due to 

small dwell time of spins in silver, spins do not experience the presence of the excitation field and hence do not show 

any peculiarity in the spin resistance signal corresponds to any kind of spin dynamics like ferromagnetic resonance 

(FMR) or electron spin resonance (ESR). Furthermore, the effect of microwave heating is studied by analyzing the 

variation of spin resistance with the applied microwave power to the antenna. 

magrawal@physik.uni-kl.de 

101



Poster 

Field orientation dependence of dynamical magnetization pinning of the main ferromagnetic 

resonance mode in a circular dot 

Gloria Rodríguez Aranda 1 , Gleb N. Kakazei 2,3 , Sergey A. Bunyaev 2 , Vladimir A. Golub 3 , Elena V. Tartakovskaya 3 , 

Andrii V. Chumak 4 , Alexander Serga 4 , Burkard Hillebrands 4 , Konstantin Gusliyenko 1,5 

1 Dpto. Física de Materiales, Universidad del País Vasco, 20018 San Sebastian, Spain; 

2 Dpto. Fisica da Faculdade de Ciencias, IFIMUP and IN – Institute of Nanoscience and Nanotechnology, Universidade do 

Porto, 4169-007 Porto, Portugal 

3 Institute of Magnetism, National Academy of Sciences of Ukraine, 03142 Kiev, Ukraine 

4Technishe Universität Kaiserslautern, 67663 Kaiserslautern, Germany 

5 IKERBASQUE,The Basque Foundation for Science, 48011 Bilbao, Spain 

A comprehensive experimental, micromagnetic and analytical investigation of high frequency magnetization dynamics 

in circular Permalloy ferromagnetic dots as a function of the external magnetic field orientation was carried out. 

We tried to establish the limits of the Kittel’s equation for the main resonance field depending on the field orientation 

and the dot sizes. Dots with diameters 2R from 500 to 4000 nm, thicknesses L = 40 and 50 nm and lattice period 

4R were prepared. Room temperature ferromagnetic resonance measurements were done at 9.85 GHz. Out-of-plane 

angular dependence of the main resonance peak was measured in the range of the field angle 0° ≤ θ ≤ 90° with 

respect to the dot plane. The experimentally observed magnetization dynamics of the main resonance mode can be 

qualitatively interpreted in terms of varying dipolar boundary conditions for the dynamic magnetization components 

at the dot lateral edges and described in the terms of pinning of the dynamical magnetization. We calculated the 

pinning parameter from micromagnetically simulated dynamical magnetization profiles, and also from geometrical 

and magnetic parameters by extension of the theory of in-plane magnetized dots. Micromagnetic simulations provide 

local demagnetizing field values that can be compared with the approximate analytical calculations. Results 

from both methods were compared to the ferromagnetic resonance measurements. The pinning parameter can be 

considered as an indicator of the uniformity of the dynamical magnetization profile and validity of the Kittel approximation. 

Regardless non-elliptic dot shape, the Kittel equation (no pinning) has good accuracy for thin dots (the aspect 

ratios thickness/radius b = L /R ≤ 0.1) within a wide range of the external field angles θ = 7-90°. Whereas, for the 

dot aspect ratios b > 0.1 and field orientations close to the dot normal (θ = 0°), the strong pinning conditions are 

more appropriate and a more detailed approach accounting inhomogeneous distribution of the dynamic magnetization 

is necessary. 

102 

gloria_rodriguez@ehu.es


Poster 

Magnetic relaxation in one-dimensional magnonic crystals 

Michael Körner 1 , Kilian Lenz 1 , Andreas Neudert 2 , Pedro Landeros 3 , Maciej Oskar Liedke 1 , Jürgen Lindner 1 , 

Jürgen Fassbender 3 


2 Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany 

3 Universidad Técnica Federico Santa María, 2390123 Valparaíso, Chile 

The magnetic relaxation in quasi 1-dimensional periodic nanostructures (magnonic crystals) is investigated by ferro- 

magnetic resonance (FMR). In thin ferromagnetic films, the magnetization dynamics are governed by intrinsic effects 

like Gilbert damping and spin-pumping but also by extrinsic effects like two-magnon scattering due to inevitable 

defect structures. By using nanoscale periodically modulated magnetic films we are able to artificially create and thus 

control those defect structures necessary to induce two-magnon scattering. The results are compared to available 

theory [1]. 

Two types of magnonic crystals have been investigated: (i) Periodical ferromagnetic hybrid structures, where the 

magnetic perturbation has been created by lithographically defined stripes and subsequent ion beam irradiation. This 

reduces the saturation magnetization in the irradiated stripes. (ii) Ferromagnetic films grown on periodically nanostructured 

templates – so called ripple templates [2] - which are created by ion beam erosion of Si(001). 

Broadband ferromagnetic resonance is used to measure the resonance linewidth ΔH for different field directions and 

frequencies. The frequency-dependent measurements with the external magnetic field aligned parallel to the stripes 

show only a linear increase of ΔH. Therefore the magnetic relaxation is purely Gilbert-like. With the magnetic field 

aligned perpendicular to the periodic structure the frequency dependence exhibits pronounced peaks due to twomagnon 

scattering induced by the dipolar stray fields of the ripples. Depending on the periodicity and film thickness 

these peak positions shift and the number of visible peaks changes as well. 

The stripe defects resemble a periodic dipolar scattering field, which couples the uniform with the final-state magnons 

in the two-magnon scattering process, thus increasing the damping.Analytical calculations of similar structures show 

the same results [1]. 

For spintronic devices it could be very interesting to have a selectively higher damping at certain frequencies - a feature 

that could be even switched-off simply by changing the external field direction. 

This work was supported by the DFG grants FA 314/6-1, FA314/3-2. 

References 

[1] P. Landeros and D. L. Mills, Phys. Rev. B 85, 054424 (2012). 

[2] M. O. Liedke, M. Körner, K. Lenz, F. Grossmann, S. Facsko, and J. Fassbender, Appl. Phys. Lett. 100, 242405 (2012). 

m.koerner@hzdr.de 

103



Poster 

104 

Bending spin waves around the corner 

Katrin Vogt 1 , Helmut Schultheiss 2 , Shikha Jain 2 , John E. Pearson 2 , Axel Hoffmann 2 , Samuel D. Bader 2 , 

Burkard Hillebrands 1 


Germany 

2 Materials Science Division,Argonne National Laboratory, 60439 Argonne, USA 

The realization of spin-wave transport in two-dimensional waveguides, including directional changes along the 

propagation path of the spin wave is of fundamental importance for the development of spintronic devices. Recent 

experiments, showing that spin waves can be manipulated via charge-based spin currents and vice versa due to spin 

torque, spin pumping, spin Hall, and spin Seebeck effects, have drawn great attention to the transport properties 

of spin waves. 

We use Brillouin light scattering microscopy to analyze spin-wave propagation in microstructured Au/Py bilayer waveguides 

that exhibit a smooth, S-shaped bend and are magnetized in two different ways: First, we apply an external 

magnetic field parallel to the microwave strip line used for exciting the spin waves. In this configuration, the orientation 

between the wave vector of the spin wave and the magnetization would need to gradually change from being 

perpendicular before, parallel inside, and again perpendicular behind the bend in order to allow propagation along 

the waveguide. In a second approach, the Oersted field generated by a direct current flowing through the gold layer 

of the waveguide aligns the magnetic moments inside the permalloy to always point along the short axis of the 

waveguide, smoothly following the curvature. Therefore, the orientation between the wave vector of the spin wave 

propagating along the waveguide and the magnetization direction remains perpendicular, even inside the bend. 

We demonstrate how the magnetic field generated by the direct current flowing in the Au/Py bilayer guides spin 

waves around the curve whereas the usage of an external magnetic field prevents spin waves from entering the bend. 

Our results will open ways not only to direct spin waves in two-dimensional microstructures but also to avoid the 

previously necessary external magnets. 

Financial support by the Carl-Zeiss-Stiftung is gratefully acknowledged. 

kvogt@physik.uni-kl.de


Poster 

Magnetization dynamics in an array of ferromagnetic oxide nanostructures 

Martin Wahler 1 , Nico Homonnay 1 , Bastian Büttner 1 , Hans-Helmuth Blaschek 1 , Christian Eisenschmidt 1 , 

Georg Schmidt 1 

1 Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany 

Ferromagnetic oxides are promising materials for device fabrication in novel microelectronic applications because of 

their high spin polarization. In order to allow for their implementation into nanoelectronics it is necessary to develop 

suitable patterning techniques and to investigate the magnetic properties and spin dynamics of the ferromagnetic 

nanostructures. 

A 20 nm thick film of the ferromagnetic oxide La Sr MnO was grown by PLD on a (001) oriented SrTiO substrate. 

0.7 0.3 3 3 

The layer was patterned into an array of 71.000.000 rectangular nanostructures with lateral dimensions of nominal 

95 nm × 200 nm on a total area of 2 mm × 5 mm. The axes of the rectangles are oriented along the magnetic hard 

axes of the LSMO layer. 

The magnetization is determined by SQUID-VSM for both the unpatterned LSMO layer and for the nanostructured 

region. Within the error bars we observe no degradation of the saturation magnetization of the nanostructures. 

Ferromagnetic resonance measurements are carried out in a coplanar waveguide setup using a modulation of the 

magnetic field and lock-in detection. Measurements are carried out at room temperature and 120 K. 

As known from literature the plane film is nearly isotropic at room temperature while at 120 K a pronounced biaxial 

in-plane anisotropy can be observed. The nanostructures also show a weak anisotropy at room temperature. At low 

temperature, however, the biaxial anisotropy of the layer is superimposed by shape anisotropy. Along the long edge 

of the rectangles the hard axis is weakened while the anisotropy along the other hard axis has increased by more 

than 1000 Oe. 

We present the results for rectangles with different crystalline orientations and micromagnetic simulations which 

show reasonable agreement with the experimental results. 

martin.wahler@physik.uni-halle.de 

105



Poster 

Comparative study on magnetic nanowire and nanotube arrays by ferromagnetic 

resonance 

Yuriy Pogorelov 1,2 , Mariana Proença 1 , Célia Sousa 1 , João Ventura 1 , João Pedro Araújo 1 , Manuel Vasquez 3 , 

Andrey Timopheev 4 , Nikolai Sobolev 4 , Gleb N. Kakazei 1,2,5 

106 

1 IFIMUP and IN–Institute of Nanoscience and Nanotechnology, Universidade do Porto, 4169-007 Porto, Portugal 

2 Dpto. Fisica da Faculdade de Ciencias, Universidade do Porto, 4169-007 Porto, Portugal 

3 Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain 

4 University of Aveiro, 3810-193 Aveiro, Portugal 

5 Institute of Magnetism, National Academy of Sciences of Ukraine, 03142 Kiev, Ukraine 

Porous alumina templates filled with either Co or Ni nanotubes (NTs) or nanowires (NWs) were prepared by a potenti- 

ostatic electrodeposition technique. Interpore distance a for all the samples was fixed at ∼105 nm and pore diameter 

D varied between 35 and 60 nm (as confirmed by scanning electron and atomic force microscopies). The length of all 

the NTs and NWs was several microns.These samples were systematically measured by continuous wave (at 9.6 GHz) 

ferromagnetic resonance (FMR) at room temperature in the full range (0° to 90°) of angles θ H between the external 

magnetic field H and the normal to the sample plane. For Ni samples, the angular dependence of the main FMR peak 

was in the H range of 0.5 to 5 kOe, while for Co samples no such peak was seen in the vicinity of θ H = 0, apparently 

due to a strong perpendicular anisotropy (proportional to the saturation magnetization M s ). But for θ H = 90°, a clear 

FMR peak was seen in the range from 6 to 8 kOe, depending on the pore diameter hence our main focus was on the 

in-plane measurements (θ H = 90°). The results can be summarized as follows: 

1. For both Ni and Co NWs, the in-plane (main peak) FMR field decreases with increasing pore diameter, in a good 

agreement with the theory accounting individual NW shape and inter-wire dipolar interactions. However, the effective 

anisotropy field H eff inferred from the Kittel fit to the experiment, does not follow the simple law H eff = 2π(3f – 1)M s 

with volumetric filling factor f = 2πD 2 /(3 1/2 a 2 ). It can be due to an additional uniaxial anisotropy (along the wire), 

either by decrease of NW effective diameter or by that the pores are not filled uniformly (also reducing f ). 

2. For both Ni and Co NTs, the in-plane (main peak) FMR field is always higher of that for NW of the same diameter, 

indicating a stronger perpendicular anisotropy of NTs vs NWs. This is also confirmed by magnetic hysteresis loops 

measured with vibrating sample magnetometry. By our calculations, this is possible when the NT wall thickness d w is 

smaller than 6 to 10 nm (depending on D ), close to measured d w values. 

3. The main FMR peak intensity for Co NTs increases drastically near θ H = 90°. This may be due to alignment of 

magnetic moments (at resonance field) only for this particular case. 

ypogorel@fc.up.pt


Poster 

Splitting of FMR dispersion relation in NiFe/IrMn/Ta/NiFe spin-valve-like 

Roberta Dutra de Oliveira Pinto, Diego Ernesto González-Chávez, Tatiana Lisboa Marcondes, Wagner de Oliveira da 

Rosa, Rubem Luis Sommer 

Centro Brasileiro de Pesquisas Físicas, 22290-180 Rio de Janeiro, Brazil 

A spin-valve is a microelectronic device in which high- and low-resistance states are realized by using both the charge 

and spin of carriers. Multiple resonant spectra have been observed in a spin-valve-like configuration measured using 

a broadband ferromagnetic resonance experiment. 

In the present case, our sample is consisted by having a free ferromagnetic layer and pinned layer system ferromagnetic/antiferromagnetic 

separated by a non-magnetic spacer, which such layers present a composition as follow NiFe 

(20 nm)/IrMn(15 nm)/Ta(5nm)/NiFe(20 nm)/Ta(3 nm). 

The sample were produced using a magnetron sputtering onto a Si(100) substrate and under an in-plane applied magnetic 

field of 200 Oe in order to induce the unidirectional anisotropy (exchange bias) in the pinned layer. Moreover, 

this field also induces a small uniaxial anisotropy in the both layers. 

Static and dynamic magnetic measurements were performed using a conventional VSM and ferromagnetic resonance 

(FMR) measurements employing a vector network analyzer FMR (VNA-FMR). The measurements have been performed 

at 0° and 90° degrees away from the exchange bias induced axis (in-plane measurements). 

Static hysteresis loop measured in the easy axis direction shows the typical spin-valve-like behavior, displaying a 

shifted response for the pinned layer and a centered response for the free layer, which indicates that there is no 

coupling field in the among the free and pinned layers. 

From the VNA-FMR measurements we can observe that the dispersion curve also present two different components. 

One, which is centered in zero, is assigned to the free layer and at the same time the other one, which display some 

shifting field, is correlated with the pinned layer having the same displacement foreseen in the hysteresis loop. 

We have also compared our experimental data with numerical calculations using as a model an FM/AFM pinned layer 

with a single FM layer obtaining a good agreement between them. From such calculations we were able to extract 

some important features as, for example, anisotropy field. 

rdutra@cbpf.br 

107



Poster 

108 

Broadband ferromagnetic resonance studies in NiFe/X (X =Cu, Ag, Ta) multilayers 

Diego Ernesto González-Chávez, Roberta Dutra de Oliveira Pinto, Tatiana Lisboa Marcondes, Rubem Luis Sommer 

Centro Brasileiro de Pesquisas Físicas, 22290-180 Rio de Janeiro, Brazil 

Magnetic multilayers consisting of stack of soft ferromagnetic layers and separated by nonmagnetic spacers have 

received much attention due to their potential for technological applications. In this work NiFe/X (X = Cu, Ag and 

Ta) multilayers have been analysed using Vector network analyser FMR (VNA-FMR). Our samples are composed by a 

permalloy ferromagnetic layer (Ni Fe ) with a constant thickness of 10nm (in each layer) whereas we have varied 

81 19 

the thickness of the metal spacer (Cu, Ag, and Ta) from 0.5 nm up to 5 nm, which were produced by magnetron sputtering. 

All samples exhibit an uniaxial induced anisotropy after production due to the applied magnetic field during 

the production. Resonance spectra were measured in the range of 0.1 GHz to 7 GHz and fields up to +/- 300 Oe. From 

such dynamic measurements, we are able to extract both real and imaginary components of magnetic susceptibility. 

Static magnetization curves were also obtained in the same field range using a VSM. Depending on the spacer thickness, 

we can clearly note two resonant peaks, at a given field, and such behavior is correlated with the previously 

magnetoimpedance measurements performed at 1.8 GHz [1].This multiple peak structure is ascribed to both acoustic 

and optical resonant modes of the coupled magnetic layers. The coupling interaction constants were obtained from 

resonant curve fittings using the dispersion relations. To calculate them, numerically, we have used a simple FM–FM 

coupled layers model, including bilinear and biquadratic exchange coupling. Amplitude and linewidth dependences, 

as a function of applied magnetic field, are also discussed for each resonant mode. 

References 

[1] A. M. H. de Andrade, R. B. da Silva, M. A. Correa, A. D. C. Viegas, A. M. Severino, and R. L. Sommer, J. Magn. Magn. 

Mater 272, 1846 (2004). 

diegogch@cbpf.br


Poster 

Magnetostatic spin waves diffraction on antidots in yttrium iron garnet films 

Ryszard Gieniusz 1 , Vladimir Bessonov 1 , Urszula Guzowska 1 , Marek Kisielewski 1 , Henning Ulrichs 2 , Alex Stognii 3 , 

Andrzej Maziewski 1 

1 Faculty of Physics, University of Białystok, 15-167 Białystok, Poland 

2 Institute for Applied Physics and Center for Nonlinear Science, University of Münster, 48149 Münster, Germany 

3 State Research and Production “Scientific and Practical Materials Research Center at the National Academy of Sciences of 

Belarus”, 220072 Minsk, Belarus 

We experimentally studied the diffraction of the magnetostatic spin waves on a single antidot and an array of the 

antidots with different diameter (mainly 50 µm) in an yttrium iron garnet film with the thickness of 4.5 µm. The 

magnetostatic spin waves were excited by an rf magnetic field generated by a 50 µm wide microstrip antenna located 

near the array of the antidots on the garnet film. The carrier wave length of the excited spin waves was comparable 

to the diameter of the antidots. The Magnetostatic spin waves, excited by the antenna and diffracted on the antidots, 

were analyzed by spatially resolved Brillouin light scattering spectroscopy, allowing two-dimensional visualization 

of the spin waves propagation. 

The diffraction patterns showed a structure with semicaustic beams directions. These directions were experimentally 

investigated as a function of the excitation frequency, the period of the array of the antidots, and the angle between 

the wave vector k and the magnetic field H.We numerically calculated these directions of the semicaustic beams from 

isofrequency lines in k -space, applying the theory of the magnetostatic spin waves in thin films. These results are 

in good agreement with the experiment. The micromagnetic simulation of the spin wave propagation in the 

patterned film was also performed. Supported by SYMPHONY project operated within the Foundation for Polish 

Science Team Programme co-financed by the EU European Regional Development Fund, OPIE 2007-2013. 

gieniusz@uwb.edu.pl 

109



Poster 

Current-induced spinwave Doppler shift study by time-resolved scanning Kerr 

microscopy 

110 

Jean-Yves Chauleau, Hans Bauer, Georg Woltersdorf, Christian Back 

Universität Regensburg, 93040 Regensburg, Germany 

Current-induced magnetization dynamics and in particular Spin-Transfer Torque (STT) are currently some of the main 

actors in spintronics. STT has been evidenced in various different approaches and geometries such as precession and 

switching of magnetic multilayers, magnetic domain wall (DW) motion or vortex core (VC) dynamics. These have 

been widely studied for more than a decade. However, in the case of continuous magnetic distributions such as DW , s 

a full control and understanding of the STT efficiency is allowed only by an unambiguous access to its key parameters, 

namely the current polarization (P ), the non-adiabatic parameter (β) and the Gilbert damping coefficient (α). DWs are fairly complicated magnetic structures whose current-induced dynamics are consequences of combination of 

those mention parameters. An alternative to standard DW or VC dynamics has been demonstrated by Vlaminck and 

Bailleul (Science 2008) where they inductively measured the current-induced shift of spinwaves resonances: spinwave 

Doppler shift. 

In this study, the influence of a spin-polarized current on magnetostatic spinwaves in Permalloy stripes is studied 

using time-resolved scanning Kerr microscopy (TRMOKE). This approach allows not only the measurement of the full 

spinwaves spectrum but also a direct magnetic imaging of the different modes present in the stripe. This is of the 

utmost importance for a microscopic experimental understanding of the non-adiabatic parameter. A full characterization 

of the different excited modes is presented as well as evidence for current-induced shift using the TRMOKE. 

jean-yves.chauleau@physik.uni-regensburg.de

Magnon Spintronics and caloritronics P34 

Poster 

Optical detection of vortex spin-wave eigenmodes in micron sized ferromagnetic 

circular dots 

Katrin Vogt 1,2 , Oksana Sukhostavets 3 , Helmut Schultheiss 1,4 , Bjorn Obry 2 , Philipp Pirro 1 , Alexander Serga 1 , 

Thomas Sebastian 1 , Julian M. Gonzalez 3 , Konstantin Y. Guslienko 3,5 , Burkard Hillebrands1 1 Fachbereich Physik and Forschungszentrum OPTIMAS,Technische Universität Kaiserslautern, 67663 Kaiserslautern, 

Germany 

2 Graduate School Materials Science in Mainz, 55128 Mainz, Germany 

3 Departamento de Física de Materiales, Universidad del País Vasco, 20018 San Sebastián, Spain 

4 Material Science Division,Argonne National Laboratory,Argonne, Illinois 60439, USA 

5 IKERBASQUE,The Basque Foundation for Science, 48011 Bilbao, Spain 

We examine the excitation of spin-wave eigenmodes in the vortex state of microsized ferromagnetic circular dots 

made of Permalloy (Ni 81 Fe 19 ) both theoretically and experimentally using Brillouin light scattering microscopy in a 

wide frequency range from 3 to 12 GHz [1]. The spatial distributions of the dynamical magnetization of single dots 

as well as the frequencies of the excited radial eigenmodes up to the mode number of n = 13 were investigated. 

The measured quantized spin-wave eigenfrequencies in dots of different radii varying from 250 nm to 2.5 µm and 

thickness of 40 nm were understood by calculations of the radially symmetric magnetostatic spin waves in the vortex 

ground state. We have used the solutions of the magnetostatic equations for the radial magnetostatic spin waves. 

These equations are valid for arbitrary dot aspect ratios (thickness/radius), which would be important in the future 

due to the tendency to decrease the lateral parameters of the ferromagnetic elements. The measured spin-wave 

eigenfrequencies are in good agreement with our calculations for the disks with different radii. Good coincidence 

between the experimental and theoretical results proves that both the low and high number spin-wave modes can 

be described by the theoretical approach developed in this paper. We demonstrate the influence of the dot radius on 

the spatial mode profiles, in particular, changes in the pinning of the dynamical magnetization at the edges and in the 

center of the dots. We have shown by the calculations that with decreasing dot radius the pinning of the eigenmodes 

weakens for the ρ component of the dynamical magnetization at the dot’s center as well as the z component at the 

dot’s edges. However, the pinning remains strong for the ρ-component of the magnetization at the edge and for the 

z component at the center of the dot. 

References 

[1] K. Vogt et al., Phys. Rev. B 84, 174401 (2011). 

sckguslk@ehu.es 

111



Poster 

112 

Spin-Hall effect influence on ferromagnetic resonance in Pt-YIG structures 

Dmytro Bozhko 1 , Oleksandr Talalaevskij 1 , Gennadii Melkov 1 , Volodymyr Malyshev 1 , Yurij Koblyanskij 1 , 

Andrii V. Chumak 2 , Alexander A. Serga 2 , Burkard Hillebrands 2 , Andrei Slavin 3 


2 Fachbereich Physik and Forschungszentrum OPTIMAS,Technische Universitaet Kaiserslautern, 67663 Kaiserslautern, 

Germany 


A two-layered structure consisting of a 2.1 µm YIG film and with a 13 nm Pt film sputtered on its surface was inves- 

tigated using the resonator technique. The FMR linewidth was found to be 5 Oe. With this method, electromagnetic 

waves reflections from the Pt layer are absent, in contrast to the external antenna excitation method. The experiment 

was carried out in the X frequency band. The dependencies of frequency and FMR linewidth on current strength J, 

its direction, and external magnetic field H 0 direction were measured. It was found that spin current, magnetic field 

and conductance current (opposite to electrons flow) directions forms a right-handed triple of vectors. With a current 

density of 10 6 A/cm 2 , a relative change in FMR linewidth reaches 10% at maximum. The FMR resonance magnetic 

field, within the limits of experimental accuracy due to the influence of Oersted field ~1 Oe, does not change. The 

physical mechanism, which causes the FMR linewidth to change, is interfacial spin scattering due to s-d exchange 

interaction between d-electrons in the YIG and s-electrons in the Pt, which are concentrated near the YIG-Pt interface 

due to the Spin Hall Effect. 

dbozhko@gmail.com


Poster 

Thermally excited magnonic spin current coherence length probed by the longitudinal 

spin-Seebeck effect in YIG 

Andreas Kehlberger 1 , René Röser 1 , Gerhard Jakob 1 , Ulrike Ritzmann 2 , Ulrich Nowak 2 , Mathias Kläui 1 

1 Universität Mainz, Institut für Physik, 55118 Mainz, Germany 

2 Universität Konstanz, 78457 Konstanz, Germany 

The spin-Seebeck effect has drawn much attention to the research of thermally induced spin currents in magnetic 

systems. In contrast to its conventional equivalent (charge Seebeck effect) the spin Seebeck effect was also measured 

in ferromagnetic insulators, which points out that underlying effect is related to the magnonic spin currents in the 

ferromagnetic system. Most thin film studies focus on lateral geometries by applying an in-plane thermal gradient. 

Recently it has been shown, that in this geometry the heat conductance between the substrate and the ferromagnetic 

film plays an important role to avoid out-of-plane thermal gradients and therefore unwanted thermoelectric effects, 

such as the anomalous Nernst effect. Our works focuses on the longitudinal spin Seebeck effect in thin Yttrium Iron 

Garnet (YIG) films. Compared to lateral setups, we can neglect the heat conductance mismatch between substrate 

and ferromagnetic film. Using a ferromagnetic insulator protects our measurements from unwanted parasitic charge 

effects. We present measurements series for different thickness YIG films, which reveal the thickness dependence of 

the spin-Seebeck effect. Combining this with theoretical calculations, we can deduce from this dependence the coherence 

length of the thermally excited magnons that carry the spin current. This work is supported by the DFG priority 

program SPP 1538 Spin Caloric Transport. 

kehlberg@uni-mainz.de 

113



Poster 

114 

Spin wave resonance in Ni 81 Fe 19 microstripes containing a mechanical gap 

Thomas Langner, Björn Obry, Thomas Brächer, Philipp Pirro, Katrin Vogt, Alexander Serga, Britta Leven, 


Fachbereich Physik and Forschungszentrum OPTIMAS,Technische Universitaet Kaiserslautern, 67663 Kaiserslautern, 

Germany 

The investigation of magnetization dynamics has attracted a lot of interest in recent research. Spin waves, the 

collective motion of magnetic moments, reveal a high potential to carry information through transport of angular 

momentum without transport of electrical charge. The manipulation of the propagation properties of spin waves is 

of high importance to develop systems in which the flow of information can be tuned for specific applications. One 

way to manipulate these properties is the use of magnetic tunnel barriers like wires with an electrical current flow 

or simply an air gap. 

We investigated the properties of dipolar surface spin waves in Ni Fe -microstripes containing an air gap. We focus 

81 19 

on the study of resonance effects that can be seen as quantized excitation between the excitation antenna and 

the tunnel barrier. 

The investigation of the spin-wave intensity properties after propagating through the gap compared to the regular 

undisturbed propagation on a reference stripe reveals a modification in the spin-wave spectrum. The wave-vector 

spectrum of the excited spin waves shows a minimum in the detected signal after propagating through the gap 

compared to a reference signal for wave vector values that correspond to a wavelength that is on the order of 

twice the distance between the antenna and the gap, thus depending on the position of the gap. By using the microfocus 

Brillouin light scattering technique the spatial distribution of the spin-wave intensity along the stripe with 

gap is investigated and compared to the spatial distribution along a stripe without any modification with respect 

to the efficiency of excitation between the antenna and the gap. 

We show results for different sets of parameters by varying the gap size, the distance between the antenna and the 

gap and the applied external magnetic field strength. 

Financial support by the Deutsche Forschungsgemeinschaft (DFG) is gratefully acknowledged. 

tlangner@rhrk.uni-kl.de


Poster 

Direct detection of magnon spin transport by the inverse spin Hall effect 

Matthias Benjamin Jungfleisch 1 , Andrii V. Chumak 1 , Alexander Serga 1 , Roland Neb 1 , Dmytro Bozhko 1,2 , 

Vasyl Tiberkevich 3 , Burkard Hillebrands 1 


Germany 



Spin pumping and inverse spin Hall effect (ISHE) are the fundamental mechanisms to convert magnons, which are 

the quanta of spin waves, into electron spin currents and consecutively into charge currents. [1] The utilization of 

spin waves in spintronics allows the transfer of spin angular momentum over centimeter distances in ferromagnetic 

insulators. So far, there is no direct evidence of the magnon transport detected by means of a combination of spin 

pumping and inverse spin Hall effect. 

In this poster, we present the conversion of traveling magnons into an electron carried spin current in a time resolved 

experiment, in which an inductive spin-wave source and an ISHE platinum detector are spatially separated. We excite 

a spin-wave packet in a ferrimagnetic yttrium-iron garnet (YIG) waveguide by a microwave source and detect it 3 mm 

apart by an attached platinum layer as a delayed ISHE voltage pulse. This delay is determined by the finite spin-wave 

group velocity and is a direct evidence of the magnon spin transport. 

In addition, the contribution of the secondary magnons, excited in the process of relaxation of the propagating spin 

waves, to the ISHE voltage is shown and estimated theoretically. These secondary waves are known to be dipolarexchange 

spin waves (DESWs), excited as a result of elastic two-magnon scattering of the traveling wave on inhomogeneities 

and impurities. [2] It turns out, that the contribution of these magnons to the ISHE voltage is comparable to 

that of the originally excited traveling magnons. They cause an additional time shift and a tailing of the ISHE voltage 

pulse. [3] The field dependent measurements show that the spin pumping efficiency in YIG-Pt heterostructures does 

not depend on the spin-wave wavenumber. The presented experiment suggests the utilization of spin waves for the 

information transfer over macroscopic distances in spintronics devices and circuits. 

Financial support by Deutsche Forschungsgemeinschaft (CH 1037/1-1) and by the Grant No. ECCS-1001815 from 

National Science Foundation of the USA is gratefully acknowledged. 

References 

[1] E. Saitoh, M. Ueda, H. Miyajima, and G. Tatara, Appl. Phys. Lett. 88, 182509 (2006). 

[2] M. Sparks, Ferromagnetic Relaxation Theory (McGraw-Hill, New York, 1964). 

[3] M. B. Jungfleisch, A. V. Chumak, V. I. Vasyuchka, A. A. Serga, B. Obry, H. Schultheiss, P. A. Beck, A. D. Karenowska, E. 

Saitoh, and B. Hillebrands, Appl. Phys. Lett. 99, 182512 (2011). 

jungfleisch@physik.uni-kl.de 

115



Poster 

116 

Magnon mediated heat transport in a magnetic insulator 

Vitaliy Vasyuchka, Alexander Serga, Andrii V. Chumak, Burkard Hillebrands 

Fachbereich Physik and Forschungszentrum OPTIMAS,Technische Universität Kaiserslautern, 

67663 Kaiserslautern, Germany 

In a magnetic system thermal gradients can appear as a natural result of thermalization of artificially excited magnons. 

Detection and measurement of such gradients provides information about the heat transport by magnon 

currents. In our experiments, the temperature gradient created by coherent surface and volume magnons excited in 

a tangentially magnetized yttrium iron garnet (YIG) film was detected using an infrared thermography technique. An 

infrared camera with high thermal sensitivity (0.05 K) and spatial resolution (40 µm) was used for the precise measurement 

of spatial distribution and evolution of magnon induced thermal fields. In the case of volume magnons the 

temperature distribution along the YIG film was found symmetrical relative to the antenna, while the thermalization 

of the surface magnons results in an unsymmetrical distribution. Moreover, the shift of the temperature maximum 

apart from the antenna was observed in the case of surface magnons. The difference in the temperature profiles is 

understood as a result of a nonreciprocal propagation of surface magnons.The time dynamics of the magnon-induced 

thermal gradients was studied. 

Financial support by the Deutsche Forschungsgemeinschaft (VA 735/1-1) within Priority Program 1538 „Spin Caloric 

Transport“ is gratefully acknowledged. 

vasyuchka@physik.uni-kl.de


Poster 

Magnon temperature measurements in magnetic insulators 

Alexander Serga 1 , Milan Agrawal 1 , Vitaliy Vasyuchka 1 , Gennady Melkov 2 , Burkard Hillebrands 1 


Germany 


The study of phonon-magnon interaction is a baseline for the new emerging field of spin caloritronics [1]. Magnon 

and phonon temperature distributions in ferromagnets can explain the thermal spin transport phenomena like spin 

Seebeck and magnon-drag effects. These phenomena have been recently studied electrically by measuring the induced 

inverse spin Hall voltage in Platinum stripes placed over the ferromagnets [2] but the underlying physics is yet 

not fully understood. Generally, in thermal gradient subjected magnetic systems, heat currents drive the hot magnons 

towards cold ones and rearrange the magnon temperature profile of system [3]. Here, we report on the measurement 

of spatial distribution of magnon temperature in magnetic insulator imposed to a lateral thermal gradient by studying 

the variation of local magnetization of the system. The local magnetization variation is detected by measuring the 

frequency shift of thermal spin-wave with temperature gradient using Brillouin light scattering (BLS) techniques. The 

measurements reveal the correlation between phonons and magnons in these kinds of materials. The experimental 

findings show that the contribution of magnons to the spin Seebeck effect, even in magnetic insulators where 

the magnon-phonon interaction is weaker compare to magnetic metal like Permalloy, is negligible or rather small. 

Furthermore, experimental data is interpreted with the existing theoretical models [3, 4] and typical length scale of 

phonon-magnon interaction is determined which is relatively small to explain the spin Seebeck effect in YIG using 

the proposed theory in Ref. [4]. 

Financial supports by the Deutsche Forschungsgemeinschaft (SE 1771/4-1) within Priority Program 1538 „Spin Caloric 

Transport“ and Graduate School of MAINZ are gratefully acknowledged. 

References 

[1] G. E. W. Bauer et al., Nature Mater. 11, 391 (2012). 

[2] K. Uchida et al., Nature 455, 778 (2008). 

[3] D. J. Sanders and D. Walton, Phys. Rev. B 15, 1489 (1977). 

[4] J. Xiao et al., Phys. Rev. B 81, 214418 (2010). 

serga@physik.uni-kl.de 

117



Poster 

118 

Spin wave propagation and transformation in a thermal gradient 

Björn Obry, Vitaliy Vasyuchka, Andrii V. Chumak, Alexander Serga, Burkard Hillebrands 

Fachbereich Physik and Forschungszentrum OPTIMAS,Technische Universität Kaiserslautern, 

67663 Kaiserslautern, Germany 

Thermal gradients have a significant influence on the spin system of magnetic materials giving rise to the flow of 

spin currents. This also applies for magnetic insulators, where spin waves play an important role in the mediation of 

spin currents. Considered in another way, a thermal gradient can act as a new method of creating, amplifying and 

manipulating spin waves. Hence, it is instructive to study the spin-wave behavior in a region with inhomogeneous 

temperature. 

We investigate the propagation behavior of spin waves in an yttrium iron garnet (YIG) waveguide under the influence 

of a thermal gradient. Therefore, in a first experiment, spin waves propagating towards a colder region have been 

investigated utilizing phase-resolved Brillouin light scattering (BLS) spectroscopy. By mapping the spatial distribution 

of the interference between the spin-wave signal and a reference signal with constant phase it is possible to observe 

with space resolution a decrease of the spin-wave wavelength to about half of its original value. The wavelength 

reduction is caused by a change in saturation magnetization which continuously changes with local temperature. 

Furthermore, a reflection of spin waves is achieved when propagating towards a hotter region. Measurements of the 

spin-wave intensity reveal the existence of two waveguide modes. For each mode a reflection point can be determined, 

behind which the spin-wave amplitude becomes evanescent. Due to the temperature increase the change in 

saturation magnetization is large enough to shift the dispersion relation out of range of the spin-wave frequency. For 

a given temperature increase, i.e. beyond a critical point of the waveguide, no spin waves can exist and propagation 

in this region is prevented. 

In conclusion the experimental findings show that manipulation of propagating spin waves by thermal gradients is 

possible, revealing the potential of thermal gradients for application in spintronic and magnon logic devices. 

Financial support by the Deutsche Forschungsgemeinschaft (DFG, VA 735/1-1) within Priority Program 1538 „Spin 

Caloric Transport“ is gratefully acknowledged. 

bobry@physik.uni-kl.de

Nonlinear Phenomena P42 

Poster 

Spin-current emission by spin pumping in a thin film YIG/Pt system: Frequency 

dependence 

Nynke Vlietstra 1 , Vincent Castel 1 , Jamal Ben Youssef 2 , Bart van Wees 1 

1 Zernike Institute for Advanced Materials and Department of Physics, University of Groningen, 9747 AG Groningen, 

Netherlands 

2 Laboratoire de Magnétisme de Bretagne, Université de Bretagne Occidentale, 29285 Brest, France 

The actuation, detection and control of the magnetization dynamics properties and spin currents in hybrid structures 

(magnetic materials/normal metal) by using the spin hall effect (SHE) and the inverse phenomenon (ISHE), spin transfer 

torque (STT) and spin pumping has attracted much attention in the last few years. We will present the frequency 

dependence of the spin current emission by spin pumping in an Yttrium Iron Garnet (YIG, 200 nm)/platinum (Pt, 15 

nm) system [1]. YIG is a ferrimagnetic insulator, grown by liquid-phase-epitaxy (LPE). It presents isotropic behavior 

of the magnetization in the plane, a small linewidth (α = 2×10-4 ), and a roughness lower than 0.4 nm. On top of the 

YIG, platinum is deposited. Platinum is used because of its strong spin-orbit coupling, which is favorable to increase 

the ISHE signal [2]. 

The system is actuated at the ferromagnetic resonance conditions, using a microstrip line in reflection, over a large 

range of frequencies. The magnetization precession in the YIG will result in a spin current pumped into the Pt-layer, 

where it creates a charge current, due to the ISHE. We investigated how the voltage signal from the spin current detector 

(Pt-layer) depends on the frequency [0.6 - 7 GHz], the microwave power, P , [1 -70 mW], and the in-plane static 

in 

magnetic field. So far, only a few groups [3, 4] presented results on the frequency dependence of the spin pumping 

process in YIG/Pt systems. 

In the frequency range [0.6-3.2 GHz] a strong enhancement of the detected ISHE-voltage is observed, contributed 

to the appearance of non-linear phenomena, which can induce the creation of spin waves with a short wavelength 

(multi-magnon processes, such as two-, three- and/or four-magnon scattering). As the dc voltage, induced by spin 

pumping, is insensitive to the spin wave wavelength, these short wavelength spin waves will also be detected, resulting 

in an enhanced signal. It is not obvious to identify the contributions of the different multi-magnon processes to 

the enhancement of the dc voltage at low frequency. However, we will discuss some possible processes and try to link 

them to the results obtained from our system. 

References 

[1] V. Castel, N. Vlietstra, J. Ben Youssef, B. J. van Wees, submitted. 

[2] K. Ando, Y. Kajiwara, K. Sasage, K. Uchida, and E. Saitoh, IEEE Trans. Mag. 46, 1331 (2010). 

[3] H. Kurebayashi, O. Dzyapko, V. E. Demidov, D. Fang, A. J. Ferguson, and S. Demokritov, Nature Mater. 3053, 620 

(2011). 

[4] Y. Kajiwara, K. Harii, S. Takahashi, J. Ohe, K. Uchida, M. Mizuguchi, H. Umezawa, H. Kawai, K. Ando, K. Takanashi, S. 

Maekawa, and E. Saitoh, Nature 464, 262 (2010). 

n.vlietstra@rug.nl 

119


Nonlinear Phenomena P43 

Poster 

Secondary self-modulation instability of microwave spin waves in ferromagnetic 

films 

120 

Alexey Ustinov 1 , Boris Kalinikos 1 , Vladislav Demidov 2 , Sergej Demokritov 2 

1 St.Petersburg Electrotechnical University, 197376 St.Petersburg, Russia 

2 University of Muenster, 48149 Münster, Germany 

Modulation instability is a nonlinear wave phenomenon which has been attracting noticeable research interest. 

This phenomenon was observed and studied in diverse physical systems such as waves on the surface of water, ionacoustic 

waves in plasma, light waves in optical fibers, microwave spin waves in magnetic films, and others [1-3]. 

This work reports the experimental observation of the secondary self-modulation instability (SMI) of the spin waves 

propagating in ferromagnetic films. The specific experiments were carried out with 2.2-µm-thick, 1.5-mm-wide, and 

40-mm-long yttrium iron garnet (YIG) film waveguide. The film was epitaxially grown on 500-µm-thick gadolinium 

gallium garnet substrate. The spin waves in the YIG film waveguide were excited and detected by microstrip transducers 

separated by a distance of 1.8 mm. The bias magnetic field of 4058 Oe was directed perpendicular to the 

YIG film plane. The YIG film had asymmetrically pinned surface spins, a ferromagnetic resonance line-width of 0.4 Oe 

at 6 GHz, and a saturation magnetization 1750 G. A distinguished feature of the film is a strong frequency dispersion 

of the spin wave group velocity and consequently the so called „dipole gaps“ are distinctive for the spin wave transmission 

[3]. During the measurements we excited an input monochromatic spin wave at the carrier frequencies in the 

vicinity of the lowest-frequency dipole gap. Then we gradually increased the input power P and observed the output 

in 

waveforms. The SMI of the carrier spin wave developed for small values of the input power in the frequency range 

of 6487-6492 MHz. At a particular frequency of 6490.5 MHz the development of the SMI resulted in the formation 

of the stationary soliton train [3]. Correspondingly, in the frequency domain we observed sidebands around the input 

carrier harmonic. The primary SMI emerged at P = 1.36 mW and had a frequency of 2.15 MHz. A further increase 

in1 

in the P led to after-modulation of the amplitude of the soliton train or, in other words, in the self-modulation 

in 

instability of the soliton train. We refer to it as the secondary SMI because it appears to be an “envelope of the 

envelope” of the initially excited monochromatic carrier spin wave. In the frequency domain we observed new small 

sidebands around each sideband created by the primary SMI. The secondary SMI emerged at P = 2.02 mW and had 

in2 

a modulation frequency of about 100 kHz. For P of more than 2.48 mW a destruction of the periodic after-modulation 

in 

of the soliton train took place and the variations in the amplitude of the carrier solitons became chaotic. 

References 

[1] V.E. Zakharov et al., Physica D 238, 540(2009). 

[2] A.B. Ustinov et al., Phys. Rev. B 81, 180406(R) (2010). 

[3] B.A. Kalinikos et al., Sov. Phys. JETP 67, 303 (1988). 

ustinov_rus@yahoo.com

RF, Microwave and Millimeter Wave devices P44 

Poster 

HEMS performed by a sensor network having an effectively wireless power supply 

Takashi Yoshikawa 

Kinki University Technical College, 518-0642 Nabarishi, Japan 

In recent days, the demand for saving energy consumption is increasing steadily. HEMS (Home Energy Management 

System) is expected as one of the promising technologies to satisfy the demand. But it is now introduced only by few 

people, not spreading into the majority. The reasons are considered that the initial cost of HEMS equipment is very 

high and they are not movable, besides the fact that many people are not interested in saving energy. 

Thus, we have proposed to introduce a sensor network system into HEMS. We have planned to equip the energy 

harvesting function into the sensor network nodes in order to get rid of batteries and AC supply cables, where the 

energy harvesting is defined as the technology that uses the environment energy such as light, heat, vibration and 

so on. 

But the problem is that those energies do not exist stably in real life. Hence, we consider the wireless power transmission 

is the best way to get the energy into the sensor network nodes because it is an anytime chargeable technology 

with no wire. Then we’ve studied the Resonant-type Wireless Power Transmission applying for HEMS as the technology 

for transmitting comparatively high power in the middle range. 

In our original study, we satisfied the matching condition between power transmitting coil and the exciting coil, and 

we’ve clarified the transmitting efficiency according to the coil dimension, figure, thickness and transmitting distance. 

Considering above all parameters we’ve discussed the possibility of no battery sensor node for HEMS under practical 

resonance coil size (10 cm diameter). Finally we’ve proposed two kinds of configuration, one is two coils (transmitting 

and receiving) configuration and three coils (transmitting and intermediate and receiving) configuration. In the first 

case transmitting distance is calculated as 0.55 m and in the second case transmitting distance is calculated as 1 m. 

The calculated value agree with measured value well. 

yoshikawa@ktc.ac.jp 

121



Poster 

122 

Design of a miniaturized X-band substrate integrated waveguide circulator 

Xiong Lin, Wang Xiaoguang, Deng Longjiang 

University of Electronic Science and Technology of China, 610054 Chengdu, China 

Based on the gyromagnetic effect of ferrite and the transmission theory of the planar structure substrate integrated 

waveguide (SIW), a X-band Substrate Integrated waveguide (SIW) circulator is based on the traditional circulator and 

the micro-strip circulator. It will be designed to a small size, relatively high-power capacity, low loss, high-density integration, 

and low cost circulator. The design of the SIW circulator geometric dimensions is 12 mm × 12 mm × 1 mm 

in this paper, the bandwidth of 30 percent at the 20 dB has been obtained for VSWR less than 1.2, it have practical 

value in engineering applications. 

forest1231300@126.com


Poster 

Modeling and simulation of passive planar structures 

Ourabia Malika 

Université des Sciences et de la Technologie Houari Boumediene, 16000 Algiers,Algeria 

An approach for modeling and numerical simulation of passive planar structures using the edge line concept is 

developed. With this method, we develop an efficient modeling technique for microstrip discontinuities. The tech- 

nique obtains closed form expressions for the equivalent circuits which are used to model these discontinuities. Then 

it would be easy to handle and to characterize complicated structures like T and Y junctions, truncated junctions, 

arbitrarily shaped junctions, cascading junctions and more generally planar multiport junctions. Another advantage 

of this method is that the edge line concept for arbitrary shape junctions operates with real parameters circuits. The 

validity of the method was further confirmed by comparing our results for various discontinuities (bend, filters) with 

those from HFSS as well as from other published sources. 

ma_ourabia@hotmail.com 

123



Poster 

A modified wavelet-based meshless method for lossy magnetic dielectrics 

at microwave frequencies 

124 

Arman Afsari, Masoud Movahhedi 

Shahid Bahonar University of Kerman, 76169-133 Kerman, Iran 

The characters of dielectrics as loss, magnetization, homogeneity and their nonlinear phenomena are some important 

concepts that must be considered to analyze those electromagnetic problems for which the electromagnetic waves 

move through dielectrics. Due to the complexity of these types of problems, there is an undoubted need to a numerical 

method that is able to model the problems, well enough with higher accuracy and lower computational cost. In this 

work, we will combine a modified multiresolution analysis (MRA) with the meshless method, in a new and mathematical 

approach to study the behavior of waves in lossy magnetic inhomogeneous dielectrics at microwave frequencies. 

It will be shown that the existing MRA has some disadvantages and non meaningful aspects in view of computational 

electromagnetics. Specifying this aspects and proposing some modifications to overcome the disadvantages of 

existing MRA for reaching a strict method of using wavelets in the meshless method in area of microwave magnetic, 

is the aim of this paper. We have selected the meshless method that is one of the newest and most powerful existing 

numerical methods as an area of using the modified MRA called computational MRA (CMRA). The use of CMRA in 

meshless methods, not only leaves all the disadvantages, but also is faster and more accurate in comparison with 

the most other numerical methods as FDM, FEM and the existing meshless methods which do not use the CMRA. 

There are two types of modifications in this work. At first, two new wavelet spaces are proposed that help model the 

discontinuity of dielectrics better than existing MRA. Then, according to Shepard’s and partition of unity methods, 

the shape functions in meshless method are proposed, directly, without any need to basis functions. We have proved 

these accuracy and fastness using CMRA in analysis of the wave propagation in complex character dielectrics. The 

results show a very good agreement with the exact solutions. 

movahhedi@ieee.org


Poster 

Propagation of spin waves excited by a microwave current: a combined phase-sensitive 

micro-focused Brillouin light scattering and micromagnetic study 

Lorenzo Fallarino 1 , Marco Madami 1 , Georg Dürr 2 , Dirk Grundler 2 , Gianluca Gubbiotti 1 , Silvia Tacchi 1 , 

Giovanni Carlotti 1 

1 CNISM, Unità di Perugia and Dipartimento di Fisica, Università di Perugia, 06123 Perugia, Italy 

2 Lehrstuhl für Physik funktionaler Schichtsysteme, Physik Department,Technische Universität München, 85748 München, 

Germany 

The excitation and the propagation of spin waves on both a continuous Ni Fe film and a two dimensional magnonic 

80 20 

crystal (bicomponent lattice formed by periodic Co nanodisks introduced in nanotroughs etched into a thin Ni Fe 80 20 

film) is investigated both experimentally and numerically. The spin waves have been excited by a microwave current 

injected into a coplanar waveguide (CPW) with finite-width ground lines, which is lithographically defined on top 

of the sample. Phase sensitive, micro-focused Brillouin Light Scattering (µ-BLS) has been employed to reveal the 

spatial profile of the propagating spin waves in the magnetostatic surface wave (MSSW) geometry. This allowed us 

to measure both the wavelength of the emitted spin waves as well as their attenuation as a function of the distance 

from the exciting antenna. 

The experimental results have been satisfactorily reproduced by means of micromagnetic simulations performed with 

the open source micromagnetic code OOMMF. The exciting microwave field used in this simulation has the spatial 

profile defined by the CPW and user-defined periodic boundary conditions were employed in order to simulate the 

extended system. The resulting space and time dependent evolution of the magnetization has been analyzed by means 

of one and two dimensional fast Fourier transform algorithm (FFT) in order to obtain the spatial profile and the 

frequency spectrum of the excited spin waves as well as their dispersion relations. Evidence is given to asymmetric 

emission from the two sides of the CPW due to the symmetry breaking related to the sense of precession of the 

dynamical magnetization, as well as to the near-field effects of the extended SW emitter. 

Funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under Grant Agreement 

No. 228673 (MAGNONICS) is gratefully acknowledged. 

lorenzo.fallarino@gmail.com 

125



Poster 

A new class of artificial magnetic materials based on a modified uniplanar series 

resonator and their implementation in original applications 

126 

Ousama Abu Safia 1 , Larbi Talbi 1 , Khelifa Hettak 2 

1 Université du Québec en Outaouais, J9A 1K9 Gatinea, Canada 

2 Communications Research Centre, K2H 8S2, Ottawa, Canada 

In this paper, a new class of artificial magnetic materials (AMMs) based on a modified well-known uniplanar series 

resonator bended to form a close square loop inclusion which contains a distributed capacitance and inductance 

is proposed. Many advantages of the proposed structure over conventional split ring resonators are discussed. Based 

on a simple transmission line theory the resonance frequency at which a deep rejection frequency band occurs with 

sharp cutoff rates beside the stopband due to the presence of negative effective permeability in the dielectric slab 

of the host transmission line in the vicinity of resonance is calculated and verified with simulated and measured 

results. Two prototype microwave devices are provided to illustrate the potentiality of the proposed inclusion; The 

first design represents a dual-band bandstop filter with centre band frequencies at 3.3 GHz and 4.3 GHz, where the 

lumped element model of this filter contains four series-connected parallel LC resonators which are implemented 

using our high Q-factor AMMs patterned in back side of CPW transmission lines.The second device represents a miniaturized 

hybrid branch line coupler; based on a well-known technique to increase the electric length of transmission 

lines by patterning the ground plane under the conductor trace in microstrip lines with the complementary, dualbehavior, 

configuration of AMMs, a miniaturization factor up to 25% is achieved compared to the conventional 

circuit. For both design examples the measured and simulated responses are in good agreement which validates our 

work. 

abuo01@uqo.ca


Poster 

A possibility of tunable soft magnetic inductive device using bias magnetic field of 

a hard magnetic film magnetized by pulsed-current method 

Yosuke Obinata 1 , Megumi Yuki 1 , Makoto Sonehara 1 , Yutaka Kuramoto 1 , Kunihiko Suzuki 1 , Kenji Ikeda 2 , 

Toshiro Sato1 1 Shinshu University, 380-8553 Nagano, Japan 

2 Taiyo Yuden Co., Ltd., 370-3347 Gunma, Japan 

Many researchers have reported the tunable RF inductive devices such as MEMS tunable air-core inductor with moving 

metal plate [1], magnetostrictive/piezoelectric combination tunable inductor [2], and DC magnetic field biasing 

tunable FMR (ferromagnetic resonance) filter [3]. 

The authors have proposed and researched a magnet based magnetic field biasing tunable RF soft magnetic device, 

which has a combination of the soft and hard magnetic film [4]. The magnetic pole of the hard magnetic film can be 

changed using magnetization controlled by a pulsed-current. Bias magnetic field is applied in the soft magnetic film 

from magnetic pole of the hard magnetic film. Hence, the permeability of the soft magnetic film can be controlled by 

changing amplitude of the pulsed-current, and after magnetization it can be maintained without the control power. In 

addition, very short current-pulse-width results in small control energy (defined as a product of the current amplitude 

and pulse-width), even when the required current pulse is large for magnetizing the hard magnetic film. 

In this study, in order to confirm a possibility of the proposed method, a 20 mm length coplanar wave guide with 

FeSiO/SiO granular multilayer soft magnetic film and FeCoSm amorphous hard magnetic film was fabricated and 

2 

evaluated. In addition, a relation between FeSiO/SiO granular multilayer soft magnetic film thickness, segment length 

2 

in magnetic film with divided structure, change in equivalent series inductance and quarter wavelength frequency in 

the tunable coplanar wave guide was investigated. 

From experimental results, in case of using 0.2 µm thick soft granular film, by changing amplitude of the currentpulse 

with 1 ms pulse-width the maximum inductance change was up to 18 %, and maximum change of the quarter 

wavelength frequency was 9.6%. The control energy for one time tuning defined as a product of amplitude of the 

current-pulse and pulse-width was small enough (5.4 µWh). And when increasing the increasing soft magnetic layer 

thickness or decreasing the segment length in magnetic film with divided structure, both the changes in equivalent 

series inductance and quarter wavelength frequency became large. 

References 

[1] H. Sugawara et al., IEICE Trans. on Fund. Electron. E92-A, 401 (2009). 

[2] M. El Bakkali et al., Microelectr. J. 42, 233 (2011). 

[3] B.Kuanr et al., IEEE Trans. Magn. 41, 3538 (2005). 

[4] M. Yuki et al., J. Magn. Soc. Jpn. 36, 229 (2012). (in Japanese). 

makoto@shinshu-u.ac.jp 

127



Poster 

Enhanced high power 360 degree ferrite phase shifter for beam steering applications 

at Ka-band 

128 

Niranchanan Suntheralingam, Imtiaz Khairuddin, Ivor Morgan, Harkanwal Deep, Colin McLaren 

Com Dev Europe Limited, HP22 5SX Aylesbury, UK 

Ferrite phase shift and control components are typically designed with low reluctance magnetic bias circuits to 

reduce size, mass and switching energy (and hence total power consumption) - all of which are critical in space based 

switching systems. One suitable geometrical arrangement is a toroidal shaped ferrite positioned symmetrically inside 

a rectangular waveguide. A 360 degrees phase length Ka- band VPS (Variable Phase Shifter) for high power space 

applications employing toroidal ferrites has been designed, manufactured, assembled and validated. A detailed 

account of an accurate finite element method using commercially available tools is presented which allows precise 

modelling of the non-uniform magnetization field concentrated within the toroid of this type of latching phase 

shifter. This model accounts for the influence of the toroid corners (an important practical consideration) in the total 

calculated phase shift of the device with a high degree of accuracy. Previously, empirical methods have been used to 

model the influence of toroid corners with relatively low degrees of accuracy. Both measured and predicted results 

are compared and the predicted phase shift is shown to be within +/-2% of the measured results. So this allows, 

utilising the techniques described, accurate prediction of the phase shift which, in turn, minimises any iteration 

of the complete phase shifter design. 

Niran.Lingham@comdev.co.uk


Poster 

Design and simulation of 505.8 MHz strip line ferrite circulator for Indus 2 

Manjeet Ahlawat, R.S. Shinde 

Raja Ramanna Centre for Advanced Technology (RRCAT), 452013 Indore, India 

Circulator is an amazing device which can couple the power entering in anyone of its ports to the next port in one 

rotation only, and offers high isolation in reverse direction. Circulators find most wide applications in RF systems as 

a duplexer, and as an isolator with third port terminated with matched load. In particle accelerators ferrite circulators 

are used for the attenuation of reflected back power from a mismatched load or cavity to RF source to avoid the 

damage of RF source. To meet this requirement a strip line ferrite circulator has been designed and simulated using 

CST MICROWAVE STUDIO at 505.8 MHz for Indus 2 applications. Circulator geometries and biasing DC fields have 

been optimized (above resonance), and good results are observed with high reflection of 27 dB, with 30 dB isolation 

and 0.4 dB insertion loss.A MATLAB program has been developed for automatic calculations of circulator geometries, 

for given frequency and design parameters. Also thermal analysis has been done by observing the temperature rise 

with input power using thermally coupled simulation in CST Microwave studio. For 1000 Watt input power maximum 

temperature in the circulator is 79°C which without any forced cooling. This paper presents the design aspects, 

calculations and electromagnetic and thermal simulation of ferrite circulator. 

mahlawat@rrcat.gov.in 

129



Poster 

130 

SOI CMOS LNA for Implantable WBAN 

Ayobami Iji 

2122 Sydney,Australia 

A low voltage, low power single-ended LNA is implemented in a 0.25µm SOI CMOS technology. A theoretical 

basis for the design is used to develop design constraints in conjunction with a layout-aware design flow providing 

early insight into parasitic. The SOI CMOS LNA has a post-layout simulated noise figure of less than 3 dB; input 

IP3 of -16 dBm and small-signal gain of 19.2 dB within the 3-5 GHz band. Total current consumption is 5.2 mA from 

1.5 V supply voltage. The LNA can also operate under 1 V supply voltage with relatively small linear performance 

degradation. Chip area is 0.89 mm 2 . Due to the high-resistivity silicon substrate, buried oxide isolation and low 

threshold voltage, SOI CMOS technology offers significant performance improvements for LNAs, which makes the 

designed LNA well suitable for implantable WBANs.

Spin-Torque Oscillators P54 

Poster 

Spin torque driven excitations in synthetic antiferromagnets 

Elmer Monteblanco 1 , Daria Gusakova 1 , Felipe Garcia Sanchez 1 , Liliana Buda-Prejbeanu 1 , Alex Jenkins 1 , 

Ursula Ebels 1 , Marie-Claire Cyrille 2 , Bernard Dieny 1 

1 CNRS SPINTEC, 38054 Grenoble, France 

2 LETI, 38054 Grenoble, France 

Large angle magnetization dynamics in nanoscale magneto-resistive devices can be induced by means of spin 

momentum transfer via a spin polarized DC current. Such a spin torque oscillator (STO) presents intrinsic non-linear 

properties such as the non-linear coupling between amplitude and frequency that allows frequency tuning, enhan- 

ces phase-locking ranges and plays a crucial role in linewidth broadening [1]. These phenomena have been widely 

studied in the past for single free layers. For read-head and magnetic random access memory (MRAM) applications, 

synthetic antiferromagnets (SAF) have been proposed, where two ferromagnetic layers are strongly coupled by an 

exchange interaction across a non-magnetic spacer layer. As reported in our previous experimental study [2] the 

linewidth in a synthetic antiferromagnet (SAF) layer can be lower than in a single free layer. In order to understand 

this result, it is important to analyze in detail the various aspects of magnetization dynamics for coupled magnetic 

layer structures. We have established the zero temperature excitation spectrum using macrospin simulations of spin 

torque driven excitations in SAF and AF/SAF structures. Here AF is an exchange bias layer. The internal stability of the 

SAF could be modified by changing the RKKY coupling between the magnetic layers. This is an important parameter 

to take into count as one possibility to reduce the linewidth. Going beyond our previous results [3], we present here 

the current-field state diagram of the excitations and the corresponding current and applied bias field dependencies 

of the frequency, as a function of the exchange coupling strength. We can identify conditions that are more suited for 

magnetic switching and MRAM applications or more suited for microwave applications. Furthermore, we can explain 

the transition of a red-shifted in-plane-precession (IPP) mode to a blue-shifted IPP mode in terms of the dynamic 

interlayer exchange coupling. 

References 

[1] A. N. Slavin and V. Tiberkevich, IEEE Trans. Magn. 45, 1875 (2009). 

[2] D. Houssameddine et al., Appl. Phys. Lett 96, 072511 (2010). 

[3] D. Gusakova et al., Phys. Rev. B 79, 104406 (2009). 

elmer.monteblanco@cea.fr 

131



Poster 

132 

Full phase diagram of spin torque oscillators with perpendicular polariser 

Alex Jenkins 1 , Bernard Rodmacq 1 , Ursula Ebels 1 , Marie-Claire Cyrille 2 , Michael Quinsat 1 , Juan Sierra 1 , 

Betrand Delaet 1 , Bernard Dieny 1 

1 CNRS Spintec, 38000 Grenoble, France 

2 LETI, 38054 Grenoble, France 

Spin torque nano-oscillators (STNOs) provide a promising alternative to existing technologies to realize frequency 

tunable nanoscale microwave oscillators. In the past years, spin torque driven excitations have been evidenced for a 

large variety of magnetic configurations, including magnetic free layers with quasi-single domain [1] or vortex type 

magnetization configurations [2-5], as well as for in-plane and out-of plane magnetized polarizing layers. 

Enhancing output power is a crucial issue for applications. This can be achieved by maximising the precession amplitude 

using for instance vortex type oscillations [2-5] or the out of plane (OPP) precession modes of a homogenously 

in-plane magnetized film [6]. The latter can be realized by combining an out-of-plane polarizer with an in-plane magnetized 

free layer.This type of perpendicular polarizer configuration has been investigated previously by our group [6] 

where the OPP mode has been clearly evidenced for low current densities. In agreement with micromagnetic simulations 

[7], two OPP branches exist. At lower current densities a macrospin type OPP branch exists, with frequencies 

that increase with current. This macrospin branch changes into an ‘onion’ or ‘C’ distortion branch, with frequencies 

that are constant or decrease with current. Simulations reveal that upon further increasing the current this distorted 

OPP branch evolves into a vortex state.The experimental studies presented here on perpendicular polarizer spin valve 

structures, explore the corresponding excitation spectra at high current densities where the OPP mode gives way to 

a new mode that is characterized by low frequency (1-2 GHz), low linewidth (~10 MHz) oscillations with multiple 

harmonic signals. These vortex oscillations are observed over a range of sample sizes and shapes. The corresponding 

phase diagram as a function of current and in-plane bias field complements the previously established one for the 

perpendicular polarizer [6,7]. These studies are indicative of the vortex oscillations predicted by our simulations. Analysis 

of the linewidth and power of the 2nd and 3rd harmonics suggest two dynamic vortex states, related to damped 

resonant and steady state oscillations It is noted that these vortex oscillations correspond to a dynamic state that is 

stabilised through the perpendicular spin polarized current, in contrast to vortex oscillations stabilised by the Oested 

field [2,4] or developing from a vortex ground state [3,5]. The authors acknowledge support from ANR-09-NANO-037 

and ANR-2011-NANO-016-07. 

References 

[1] Kiselev et al., Nature 425, 380 (2003). 

[2] M. R. Pufall et al., Phys. Rev. B 75, 140404 (2007). 

[3] V. S. Pribiag et al., Nature Phys. 498, 3 (2007). 

[4] Q. Mistral et al., Phys. Rev. Lett. 100, 257201 (2008). 

[5] A. Dussaux et al., Appl. Phys. Lett. 98, 062501 (2011). 

[6] D. Houssameddine et al., Nature Mat. 6, 447 (2007). 

[7] I. Firastrau et al., Phys. Rev. B 78, 024437 (2008). 

alex.jenkins@cea.fr


Poster 

Double-mode vortex dynamics in nanocontact spin-torque oscillators 

Yevgen Pogoryelov 1 , Sohrab Sani 2 , Majid Mohseni 2 , Johan Persson 3 , Ezio Iacocca 1 , Johan Åkerman 1,2 



3 NanOsc AB, 16440 Stockholm, Sweden 

Magnetic vortex oscillations excited by dc currents, through the spin-torque effect, have been experimentally studied 

both in nano-pillar and nano-contact spin-valve (SV) multilayers. Under certain conditions the circular Oersted field 

associated with the current flowing through the nanocontact can trigger the nucleation of a magnetic vortex even at 

zero applied external magnetic field. This vortex is subsequently driven into a steady-state motion by the spin torque 

[1,2]. Experimental studies of the magnetic vortex dynamics in nano-contact spin-torque oscillators (NC-STOs) show 

a complex behavior and some of the observed phenomena still remain controversial [1,3]. 

In this work, we experimentally study the appearance of the double-mode vortex state both in frequency and time 

domain. The device studied here consists of a 250 nm diameter nanocontact, fabricated on top of a continuous 

8-16 µm 2 SV mesa comprised of the following layers: Cu(15 nm)/Co(8 nm)/Cu(7 nm)/NiFe(4.5 nm)/Cu(3 nm). Applied 

dc currents range from 1 to 40 mA. Measurements of the vortex dynamics are performed both at zero and small 

out-of-plane fields (up to 500 Oe). 

Frequency-domain measurements showed that the double-mode vortex state exists in the range of dc currents 

from about 15 mA up to 25-30 mA, while the vortex nucleation current is around 10 mA. In Ref. 3, where a similar 

SV structure with unpinned fixed layer was studied, it was suggested that the double-vortex mode may be due 

to the generation of the vortex oscillation in the fixed layer. This assumption was also indirectly supported by a later 

experimental study [4] where the fixed layer was pinned resulting in a single mode precession and voltage waveform 

close to sinusoidal. 

However, our time-domain studies clearly show that the two modes (165 and 207 MHz respectively; I = 23.4 mA) are 

not excited simultaneously. Instead, the signal exhibits mode hopping with characteristic dwell times on the order 

of 100 ns. If the second mode is indeed related to vortex motion in the fixed layer, our results indicate that the excitation 

jumps back and forth between the free and the fixed layer. An alternative explanation might be found in the suggested 

formation of a vortex-antivortex (V-AV) pair in the free layer, with a different dynamics than a single vortex [5]. 

Since the V-AV pair is unstable on longer time-scales, this would explain the experimentally observed mode-hopping. 

References 

[1] M. R. Pufall, W. H. Rippard, M. L. Schneider, and S. E. Russek, Phys. Rev. B 75, 140404 (2007). 

[2] Q. Mistral, M. van Kampen, G. Hrkac, et al., Phys. Rev. Lett. 100, 257201 (2008). 

[3] M. Kuepferling, C. Serpico, M. Pufall, et al., Appl. Phys. Lett. 96, 252507 (2010). 

[4] T. Devolder, J.-V. Kim, P. Crozat, et al., Appl. Phys. Lett. 95, 012507 (2009). 

[5] D. V. Berkov and N. L. Gorn, Phys. Rev. B 80, 064409 (2009). 

pogoryelov@gmail.com 

133



Poster 

Consequences of the Oersted field induced asymmetric energy landscape 

in nanocontact spin torque oscillators 

Randy Dumas 1 , Stefano Bonetti 2 , Ezio Iacocca 1 , Sohrab Sani 3 , Majid Mohseni 3 , Anders Eklund 3 , Johan Persson 4 , 

Olle G. Heinonen 5 , Johan Åkerman 1,3 


2 Stanford University, 94305 Stanford, USA 


4NanOsc AB, 16440, Stockholm, Sweden 

5 Materials Science Division and Department of Physics and Astronomy, Argonne National Laboratory and Northwestern 

134 

University, 60439 IL, Lemont, USA 

The emerging field of magnonics relies on the systematic generation, manipulation, and detection of spin waves. Nanocontact 

spin torque oscillators provide an ideal platform to study spin transfer torque induced spin wave emission 

and offer many advantages as spin wave emitters, compared to standard inductive techniques.As previously reported 

[1-3], a propagating spin wave mode is present for all applied field angles and exists above the FMR frequency. 

However, below a critical angle, θ , a self-localized spin wave mode, with a frequency below the FMR also exists. 

C 

Simulations then reveal a highly deterministic mode-hopping between the two. 

Here, a detailed study of the critical role played by the spatially inhomogeneous Oersted field generated under the 

nanocontact is presented. Broadband electrical measurements reveal a low frequency (f < 2 GHz) signal that allows 

for a detailed study of the angular dependence of the aforementioned mode-hopping. Near θ the power spectrum is 

C 

consistent with a highly stochastic two-state switching between the propagating/localized modes. However, for lower 

angles a more periodic mode-hopping manifests itself, consistent with prior simulations. Most surprisingly, as the 

applied field angle is lowered further the low-f mode hopping feature disappears, consistent with mode coexistence. 

Simulations reveal that the propagating/localized modes are shifted towards opposite sides of the nanocontact. This 

can be understood as a consequence of the magnetostatic interaction between the Oersted field induced field gradient 

and effective dipole moment of each mode. The physical separation between the modes promotes coexistence 

at reduced field angles. 

Support from The Swedish Research Council (VR), The Swedish Foundation for Strategic Research (SSF), and the Knut 

and Alice Wallenberg Foundation is gratefully acknowledged.Argonne National Laboratory is a US DOE Science Laboratory 

operated under contract no. DE-AC02-06CH11357 by UChicago Argonne, LLC. 

References 

[1] G. Gerhart, E. Bankowski, G. A. Melkov, V. S. Tiberkevich, and A. Slavin, Phys. Rev. B 76, 024437 (2007). 

[2] S. Bonetti, V. Tiberkevich, G. Consolo, G. Finocchio, P. Muduli, F. Mancoff, A. Slavin, and J. Åkerman, Phys. Rev. Lett. 

105, 217204 (2010). 

[3] M. Madami, S. Bonetti, G. Consolo, S. Tacchi, G. Carlotti, G. Gubbiotti, F. B. Mancoff, M. A. Yar, and J. Åkerman, 

Nature Nanotechnology 6, 635 (2011). 

randydumas@gmail.com


Poster 

Parametric excitation in a magnetic tunnel junction-based spin torque oscillator 

Philipp Dürrenfeld 1 , Pranaba Muduli 1 , Johan Åkerman 1,2 

1 Department of Physics, University of Gothenburg, 412 96 Gothenburg, Sweden 


Spin torque oscillators (STO) are nano-scale devices capable of emitting microwave oscillations due to spin transfer 

effects [1-2]. Recently a new phenomenon of parametric excitation is demonstrated in a nanocontact metallic-based 

STO [3]. In that work the authors show parametric excitation by applying a microwave magnetic field of frequency 

f e equal to twice the resonance frequency f 0 of the nanomagnet. The technique provides a new way of studying 

magnetization dynamics. 

However, so far parametric excitation has not been demonstrated using microwave current. Here we show a first 

evidence of parametric excitation using a microwave current in a magnetic tunnel junction (MTJ) nanopillar [4]. 

The parametric excitation is observed as an increase of total power of the signal, when the injected frequency feis 

approximately twice the frequency f of the MTJ-STO. The increase of integrated power is directly proportional to 

0 

the injected microwave power and the rate of its increase is proportional to the power p of the STO in the absence 

0 

of any microwave current, which is consistent with the prediction of parametric excitation. In addition, the threshold 

of microwave current for the onset of the parametric excitation decreases with increasing bias current in agreement 

with Ref. 3. We demonstrate parametrically excited signals with an integrated power of up to 50 nW for a free 

running power of p = 10 nW. The parametrically generated signal has a linewidth which is significantly lower than 

0 

the linewidth of the free-running STO and we show a linewidth of 185 kHz, which is two orders of magnitude lower, 

compared to the free-running STO.This value is also significantly lower than that of a recent work on injection locking 

in MTJ-STO, where the minimum linewidth was limited to 35 MHz [5]. Finally we propose that an MTJ-STO can be used 

as a parametric down converter using the principle of parametric excitation. 

Support from the Swedish Foundation for Strategic Research, the Swedish Research Council, the Göran Gustafsson 

Foundation and the Knut and Alice Wallenberg Foundation are gratefully acknowledged. Johan Åkerman is a Royal 

Swedish Academy of Sciences Research Fellow supported by a grant from the Knut and Alice Wallenberg Foundation. 

References 


[2] J. Slonczewski, J. Magn. Magn. Mater. 159, L1 (1996). 

[3] S. Urazhdin, V. Tiberkevich, and A. Slavin, Phys. Rev. Lett. 105, 237204 (2010). 

[4] P. K. Muduli, O. G. Heinonen, and J. Åkerman, Phys. Rev. B 83, 184410 (2011). 

[5] M. Quinsat, et al., Appl. Phys. Lett. 98 (2011). 

philipp.durrenfeld@physics.gu.se 

135



Poster 

136 

Spin-torque nano-emitters for magnonic applications 

Vladislav Demidov 1 , Henning Ulrichs 1 , Sergej Demokritov 1 , Sergei Urazhdin 2 

1 University of Muenster, 48149 Muenster, Germany 

2 Emory University,Atlanta, GA 30322, USA 

Spin-torque nano-oscillators (STNOs) are capable of on-chip conversion of dc current into microwave-frequency 

magnetization oscillations. Since STNOs do not require external sources of microwaves, they are free from shortco- 

mings of inductive sources traditionally used for excitation of spin waves in magnonic devices, and therefore have 

a significant technological potential as nano-scale spin-wave emitters for magnonic applications. Recent experiments 

resolved a long-standing question of whether STNOs can emit spin waves at all, but their emission was either ineffici- 

ent or require application of strong out-of-plane static magnetic fields making the devices impractical. 

Here, we demonstrate a modified design of STNOs that operate at moderate magnetic fields applied in the mag- 

netic film plane and exhibit efficient emission of spin waves. These characteristics are achieved by incorporating 

an additional microscopic magnet into the STNO device. The micromagnet locally compensates the inhomogeneity 

of internal magnetic fields that causes localization, shifting the oscillation frequency upward into the range favourab- 

le for excitation of propagating spin waves. As a result, spin waves emitted by the test devices show large propagation 

lengths sufficient for implementation of magnonic circuits. Moreover, the spectral anisotropy induced by the in-plane 

magnetic field results in focussing of spin wave emission into a directed beam, enabling highly efficient directional 

transmission of signals for magnonic applications. 

References 

[1] V. E. Demidov, S. Urazhdin, and S. O. Demokritov, Nature Mater. 9, 984-988 (2010). 

[2] V. E. Demidov, S. Urazhdin, V. Tiberkevich, A. Slavin, and S. O. Demokritov, Phys. Rev. B 83, 060406(R) (2011). 

[3] H. Ulrichs, V. E. Demidov, S. O. Demokritov, and S. Urazhdin, Appl. Phys. Lett. 100, 162406 (2012). 

demidov@uni-muenster.de

lIST OF AuThORS 

137


Abrudan, Radu B05-I 

Abu Safia, Ousama P49 

Adam, Douglas J. B01-P 

Adenot-Engelvin, Anne-Lise B15-C, P03 

Adeyeye, Adekunle P11, P17 

Adur, Rohan P23 

Aeschlimann, Martin C12-C 

Afsari, Arman P47 

Agrawal, Milan P24, P40 

Ahlawat, Manjeet P52 

Ahmad, Ehsan B02-I 

Aiyar, R.P.R.C. P06 

Åkerman, Johan C15-I, C16-C, P56, P57, P58 

Albrecht, Michele C09-I 

Alebrand, Sabine C12-C 

Altimime, Laith C03-C 

Ando, Yasuo B19-C, C11-C 

Ansermet, Jean-Philippe A04-C 

Araújo, João, Pedro P29 

Arkady, Zhukov P09 

Au, Yat-Yin B02-I 

Babayan, Vladimir P08 

Back, Christian P33 

Bader, Samuel D. P27 

Bailleul, Matthieu C05-I, P11, P21 

Bali, Rantej P17 

Barnes, Stewart E. A04-C 

Barthelemy, Marie C09-I 

Bauer, Hans P33 

Belova, Lyubov A08-C 

Ben Youssef, Jamal A02-I, B07-C, P42 

Benner, Hartmut A07-I 

Bernert, Kerstin C04-C 

Bessonov, Vladimir P32 

Bhat, Vinayak A09-C 

Bhoi, Biswanath P06 

Bigot, Jean-Yves C09-I, C13-C 

Blanca, Hernando P09 

Blaschek, Hans-Helmuth P28 

Bobo, Jean Francois B07-C 

Bonetti, Stefano P57 

Bose, Thomas P12 

Boust, Fabrice B07-C 

Bozhko, Dmytro P35, P38 

Brächer, Thomas B19-C, P22, P37 

Brüssing, Frank B05-I 

Buda-Prejbeanu, Liliana P54 

138 

Bunyaev, Sergey A.12-C, P25 

Burns, Lee B03-I 

Busch, Kurt A07-I 

Büttner, Bastian P28 

Cao, Zhenhua P04 

Cardoso, Susana A12-C 

Carignan, Louis-Philippe B16-C 

Carlotti, Giovanni P48 

Castel, Vincent A02-I, P42 

Chi, Kai-Hung B12-C 

Chang, Crosby P11 

Chappert, Claude C03-C 

Charls, Simon P10 

Chauleau, Jean-Yves P33 

Chen, Yajie B03-I 

Chizhik, Alexander P09 

Chumak, Andrii P19, P25, P34, P38, P39, P35 

Chun Choi Byung A10-C 

Chung, Sunjae C15-I 

Cinchetti, Mirko C12-C 

Cyrille, Marie-Claire P54, P55 

Daigle, Andrew B03-I 

da Rosa, Wagner de Oliveira P30 

Das, Subrat Kumar A10-C 

Davison, Toby B02-I 

Deac, Alina M. C04-C, C15-I 

Deep, Harkanwal P51 

Delaet, Betrand P55 

DeLong, Lance A09-C 

Demidov, Vladislav C10-C, C14-I, P18, P43, P59 

Demokritov, Sergej C10-C, C14-I, P18, P43, P59 

Deng, Longjiang B11-C, B14-C, P01, P02, P04 

Devolder, Thibaut C03-C 

Dieny, Bernard P54, P55 

Dmytriiev, Oleksandr B02-I 

Dominguez, Lourdes P09 

Dumas, Randy P57 

Dürr, Georg P48 

Dürrenfeld, Philipp P58 

Dvornik, Mykola B02-I 

Dzyapko, Oleksandr C10-C 

Ebels, Ursula P54, P55 

Ebert, Hubert P20 

Eisenschmidt, Christian P28 

Eklund, Anders P57 

Endo, Yasushi B10-I 

Fallarino, Lorenzo P48

Fang, Dong C10-C 

Fangohr, Hans A11-C 

Farle, Michael P17 

Fassbender, Jürgen C04-C, P17, P26 

Ferguson, Andrew C10-C 

Filimonov, Yuri P14, B09-I 

Flatté, Michael B08-C 

Fowley, Ciaran C04-C 

Freitas, Paulo A12-C 

Fukami, Shunsuke C08-C 

Fukuma, Yasuhiro P24 

Gan, Huadong C04-C 

Garcia Sanchez, Felipe P54 

Garcia, Alberto B07-C 

Garcia, Javier P09 

Garifullin, Ilgiz B05-I 

Geiler, Anton B03-I 

Gieniusz, Ryszard P32 

Giovanni, Carlotti C02-I 

Golub, Vladimir A. P25 

González, Julián P09 

González, Julian M. P34 

González, Lorena P09 

González-Chávez, Diego Ernesto P30, P31 

Grigoryeva, Natalia P05 

Grishin, Sergey V. B18-I 

Grundler, Dirk P48 

Gubbiotti, Gianluca P48 

Guo, Feng A08-C 

Gusakova, Daria P54 

Gusliyenko, Konstantin P25, P34 

Guzowska, Urszula P32 

Hadimani, Ravi P02 

Hamann, Christine P23 

Hammel, P. Chris P23 

Han, Mangui B11-C, P01, P02, P04 

Harris, Vincent B03-I 

Hastings, Todd A09-C 

Heinonen, Olle G., P57 

Heinrich, Bretislav A01-P 

Hettak, Khelifa P49 

Hillebrands, Burkard B19-C, P19, P22, P24,P25, P27, 

P34, P35, P37, P38, P39, P40, P41 

Hinzke, Denise C06-I 

Hoefer, Mark C15-I 

Hoeppe, Ulrich A07-I 

Hoffmann, Axel P27 

Homonnay, Nico P28 

Iacocca, Ezio P56, P57 

Idzuchi, Hiroshi P24 

Iji, Ayobami P53 

Ikeda, Kenji P50 

Ipatov, Mihail P09 

Ishiwata, Nobuyuki C08-C 

Jain, Shikha P27 

Jakob, Gerhard P36 

Jenkins, Alex P54, P55 

Joshi, Rajeev S. A11-C 

June-Seo, Kim A13-C 

Jungfleisch, Matthias Benjamin P38 

Kakazei, Gleb N. A12-C, P25, P29 

Kalinikos, Boris B17-I, P05, P43 

Kamantsev, Alexander P13 

Kavas, Huseyin B13-C 

Kawada, Yuki C11-C 

Kehlberger, Andreas P36 

Ketterson, John A09-C 

Khairuddin, Imtiaz P51 

Khivintsev, Yuri V. B09-I, P14 

Kim, Jiwan C13-C 

Kim, Joo-Von C03-C 

Kiran, Singh P10 

Kisielewski, Marek P32 

Kittl, Jorge C03-C 

Kläui, Mathias A13-C, P36 

Koblyanskij, Yurij P35 

Koedderitzsch, Diemo P20 

Koledov, Victor P13 

Komineas, Stavros C17-C 

Körner, Michael P26 

Kostylev, Mikhail P11, P17, P18, P19 

Kozakova, Zuzana P08 

Krawczyk, Maciej P14 

Kruglyak, Volodymyr B02-I 

Kubota, Takahide B19-C 

Kumar, Ashok A10-C 

Kumar, Nikhil P15 

Kumar, P.S. Anil A11-C 

Kuramoto, Yutaka P50 

Kurebayashi, Hidekazu C10 

Kuritka, Ivo P08 

Lagae, Liesbet C03-C 

Lahderanta, Erkki B04-C 

Landeros, Pedro P26 

139


Langner, Thomas P37 

Laur, Vincent C07-C 

Lebedev, Gor C07-C 

Lee, Inhee P23 

Lee, Kyung-jin C08-C 

Lee, Seo-won C08-C 

Lefevre, Christophe P03 

Lenz, Kilian P17, P26 

Lepetit, Thomas B15-C 

Leven, Britta P22, P37 

Liedke, Maciej Oskar P26 

Lin, Xiong P45 

Lindner, Jürgen P17, P26 

Lisenkov, Ivan B06-C 

Longjiang, Deng P45 

Lopez-Diaz, Luis A13-C 

Loubens, Grégoire de A06-I 

Lu, Haipeng B14-C 

Madami, Marco P48 

Malléjac, Nicolas B15-C 

Malyshev, Volodymyr P35 

Manfrini, Mauricio C03-C 

Mankovskyy, Sergeiy P20 

Marcondes, Tatiana Lisboa P30, P31 

Martinez, Eduardo A13-C 

Maziewski, Andrzej P32 

McCord, Jeffrey P23 

McLaren, Colin P51 

McMichael, Robert A08-C 

Melkov, Gennadii P35, P40, B20-C 

Menard, David B16-C 

Mohseni, Majid C15-I, P56, P57 

Monteblanco, Elmer P54 

Morgan, Ivor P51 

Movahhedi, Masoud P47 

Mruczkiewicz, Michal P14 

Muduli, Pranaba C15-I, C16-C, P58 

Muroga, Sho B10-I 

Naganuma, Hiroshi B19-C, C11-C 

Nagata, Makoto B10-I 

Neb, Roland P38 

Neige, Julien B15-C, P03 

Neudert, Andreas P17, P26 

Nguyen, T. N. Anh C15-I 

Nicolas, Biziere B07-C 

Nikitov, Sergei A. B06-C, B09-I, P14, B18-I 

Nowak, Ulrich C06-I, P36 

140 

Obinata, Yosuke P50 

Obry, Björn P22, P34, P41, P37 

Obukhov, Yuri P23 

Ono, Teruo C08-C 

Oogane, Mikihiko B19-C, C11-C 

Ortiz, Guillermo B07-C 

Otani, Yoshichika A03-I, P24 

Otxoa, Ruben C03-C 

Ourabia, Malika P46 

Papa, Elisa A04-C 

Pavlov, Evgenii B09-I 

Pearson, John E. P27 

Pelekhov, Denis V. P23 

Persson, Johan C15-I, P56, P57 

Petit-Watelot, Sébastien C03-C 

Pham-Thi, Mai C07-C 

Pinto, Roberta Dutra de Oliveira P30, P31 

Pirro, Philipp B19-C, P22, P34, P37 

Platonov, Sergey B06-C 

Pogorelov, Yuriy A12-C, P29 

Pogoryelov, Yevgen C15-I, P56 

Polushkin, Nikolay A05-C, P16 

Pourroy, Geneviève P03 

Prabhakar, Anil A11-C, P15 

Prasad, Shiva P06 

Proença, Mariana P29 

Qin, JunFeng B11-C 

Queffelec, Patrick C07-C 

Quinsat, Michael P55 

Radu, Florin B05-I 

Raolison, Zo P03 

Rasoanoavy, Faliniaina C07-C 

Ritzmann, Ulrike C06-I, P36 

Rodmacq, Bernard P55 

Rodríguez Aranda, Gloria P25 

Romanenko, Dmitrii V. B18-I 

Römer, Florian M. P17 

Röser, René P36 

Rozanov, Konstantin B11-C 

Sakharov, Valentin K.B09-I, P14 

Salikhov, Ruslan B05-I 

Samarin, Sergey P11 

Sanches Piaia, Monica C09-I 

Sangaraju, Sambasivam A10-C 

Sani, Sohrab C15-I, P56, P57 

Sato, Toshiro P50 

Schmidt, Georg P28

Schultheiss, Helmut P27, P34 

Sebastian, Thomas B19-C, P34 

Sekiguchi, Koji C08-C 

Seo, Soo-man C08-C 

Serga, Alexander B19-C, P19, P22, P24, P25, P34, 

P35, P37, P38, P39, P40, P41 

Sharaevskii, Yurii P. B18-I 

Shavrov, Vladimir P13 

Shinde, R.S. P52 

Sierra, Juan P55 

Sietsema, Glade B08-C 

Sklenar, Joseph A09-C 

Slavin, Andrei B20-C, C01-P, P35 

Slobodianiuk, Denys B20-C 

Sluka, Volker C04-C 

Snoeck, Etienne B07-C 

Sobolev, Nikolai A12-C, P29 

Sokolov, Alexander B03-I 

Sommer, Rubem Luis P30, P31 

Sonehara, Makoto P50 

Sousa, Célia P29 

Stärk, Martin A13-C 

Steil, Daniel C12-C 

Stognii, Alex P32 

Su, Zhijuan B03-I 

Subhash, Thota P10 

Sukhostavets, Oksana P34 

Suntheralingam, Niranchanan P51 

Suzuki, Kunihiko P50 

Tacchi, Silvia P48 

Talalaevskij, Oleksandr P35 

Talbi, Larbi P49 

Tanaka, Satoshi B10-I 

Tartakovskaya, Elena V. P25 

Thiaville, André B15-C 

Thota, Subhash A10-C 

Tiberkevich, Vasyl B20-C, C01-P, P19, P38 

Timopheev, Andrey A12-C, P29 

Trimper, Steffen P12 

Trzaskowska, Aleksandra P07 

Tsai, Chen B12-C 

Ulrichs, Henning P32, P59 

Urazhdin, Sergei P59 

Ustinov, Alexey B04-C, P43 

Vader, Taco C08-C 

Valentina, Zhukova P09 

van Wees, Bart A02-I, P42 

Van Roy, Win C03-C 

Vasquez, Manuel P29 

Vasyuchka, Vitaliy P19, P39, P40, P41 

Venkat, Guru A11-C 

Venkataramani, N. P06 

Venkateswarlu, Dasari A11-C 

Ventura, João P29 

Viala, Bernard C07-C 

Vittoria, Carmine B03-I 

Vlietstra, Nynke A02-I, P42 

Vogt, Katrin P27, P34, P37 

Vomir, Mircea C09-I, C13-C 

Vukadinovic, Nicolas B07-C, B15-C, P03 

Vysotsky, Sergey B09-I 

Wagner, Kai P17 

Wahler, Martin P28 

Wang, Jianwei B03-I 

Westerholt, Kurt B05-I 

Wilfrid, Prelier P10 

Wolff, Cristian A07-I 

Woltersdorf, Georg P33 

Woods, Justin A09-C 

Xiaoguang, Wang P45 

Xie, Jianliang B14-C. P01 

Yamada, Keisuke C08-C 

Yamaguchi, Masahiro B10-I 

Yoon, M.S. Jungbum A13-C 

Yoshikawa, Takashi P44 

You, Chun-Yeol A13-C 

Yuki, Megumi P50 

Zabel, Hartmut B05-I 

Zhang, Huibin B14-C 

Zhang, Li P01 

Zhou, Peiheng B14-C, P01 

Zhu, Yun B12-C 

141


Notes 

142

Notes 

143


Notes 

144

Notes 

145

Busverbindungen vom Rathaus zur Universität: 

Linie 105, (über Hauptbahnhof) Richtung Konrad-Adenauer-Str., Haltestellen Hermann-Löns-Str., Universität Ost (Gebäude 52), Universität Süd (Gebäude 44) 

Linie 106, Richtung Mölschbach, Haltestelle Abzweig Universität 

Linie 107, (über Hauptbahnhof) Richtung Casimirring, Haltestelle Hermann-Löns-Str. 

Linie 114, Richtung Rauschenweg/Universitätswohngebiet, Haltestelle Davenport-Platz 

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Building 42 

Conference Venue 

Uni-Süd 

Linien 105 und 115 

Uni-Süd 


Uni-Ost 


Abzweig Uni 

Linien 105, 106 und 114 

bus stops 

Davenportplatz 


Uni-Ost 


Building 30 

lunch facilities 

Uni-Sporthalle 

Linie 115 

26 

bus stop of 

shuttle busses 

Pestalozzischule 

Linie 105 

Hermann-Löns-Str. 

Linien 105 und 107

2012 IEEE ICMM - proCampus GmbH

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