Workshop book - Physikzentrum der RWTH Aachen - RWTH Aachen ...

PROGRAM BOOK
International workshop on
Spin-Orbit and Interaction Effects
in Nano-Electronics
Aachen, 4-6 February, 2013
Organizers:
Sabine Andergassen, Fabian Hassler, Dirk Schuricht, Maarten Wegewijs
1

Table of contents
What comes with this booklet . . . . . . . . . . . . . . . . . . . . . . . . . 3
Organization and funding . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Getting to the institute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Workshop lecture hall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Internet access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Lunch information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Conference dinner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Talk program & abstracts . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Talks Monday February 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Talks Tuesday February 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Talks Wednesday February 6 . . . . . . . . . . . . . . . . . . . . . . . . . 47
Poster program & abstracts . . . . . . . . . . . . . . . . . . . . . . . . . 57
Posters Monday February 4 . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Posters Tuesday February 5 . . . . . . . . . . . . . . . . . . . . . . . . . . 71
List of participants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
2

What comes with this booklet
With this booklet you should have received
• Aachen city plan - Stadtplan Aachen
• Aachen information booklet - Aachen at a glance 2013
which includes restaurant information
If not, please ask at the reception of your hotel !
Please check the workshop website for updates:
http://www.physik.rwth-aachen.de/workshop2013/
• Corrections
• Electronic files of talks and posters
3

Organization and funding
The conference is organized by
• Sabine Andergassen (Universität Wien)
• Fabian Hassler (RWTH Aachen University)
• Dirk Schuricht (RWTH Aachen University)
• Maarten Wegewijs (Forschungszentrum Jülich)
with administrative support by Julia Heuerz-Sengül, Gabriele Meeßen and
technical support by Uwe Kahlert.
The workshop is funded by
• The European Science Foundation (ESF),through the Research Networking
Programme Quantum Spin Coherence and Electronics
http://www.esf.org/activities/research-networking-programmes/physical-and-engineering-sciences-pesc/currentresearch-networking-programmes/quantum-spin-coherence-andelectronics.html
• DFG Research Unit 912 Coherence and Relaxation Properties of Electron
Spins
http://www.spintransport.de
4

Getting to the institute
(1) If you are staying at Hotel Marschiertor (down town)
Monday:
• Someone from the workshop will pick up a group at the hotel
• To join the group you need to buy bus tickets yourself beforehand
(to avoid ∼ 50 people annoying the bus driver at once):
◦ A ticket machine is located at the central station at the bus
stop and also at the Tabak & Zubehör Shop from T. H. Kleen
on your left when you exit the central station on the side of the
big square.
◦ For the entire workshop you need 6 tickets
2 x single trip (2.50 Euro) + 1x four trips (8.80 Euro) = 13.80 Euro
• Travel time to the institute is about 30 minutes:
The group will leave the hotel strictly at 8.00 to make it in time.
Tuesday-Wednesday:
• Take bus number 3 A or 3 B at central station (Hauptbahnhof )
(Don’t worry that these busses depart in opposite directions.
Also, depending on the departure time, you may need to change bus once)
• Your destination is Campus Melaten
• Exiting the bus, go up the stairs towards the ugly building with yellow
on the roof (Physikzentrum) which has 26 written on it in big letters.
• Enter the tower and go to lecture hall 28 D001 (Hörsaal Physik) on
the 1st floor.
5

(2) If you are staying at the RWTH-Guesthouse
Travel time to the institute is about 15 minutes on foot.
Monday: particant Fabian Heidrich-Meisner will bring a group to the institue.
The group will leave the guesthouse strictly at 8.15 to make it in time.
Tuesday-Wednesday:
• Exiting the reception of the RWTH-Guesthouse, turn left on the
Melatener Strasse and follow it all the way: you will cross an intersection
with Halifaxtrasse and finally continue across a bridge over
the highway (Pariser Ring).
• Descent from the bridge and on go up the stairs to the ugly looking
building with yellow on the roof (Physikzentrum). You will see it has
28 written on it in big letters.
• Enter the building and go to lecture hall 28 D001 (Hörsaal Physik) on
the 1st floor.
6

Workshop lecture hall
• The workshop talks take place in the main lecture hall,
28D 001 Hörsaal Physik, on the 1st floor
Just follow the signs.
• The poster sessions take place in front of the lecture hall.
7

Internet access
Power: all seats in the lecture hall are equipped with a power outlet.
Wireless internet:
• If you have an eduroam account:
simply log on as usual
• In all other cases, you can make use of a special workshop guest
account.
Simply fire up your browser, and try to go to an arbitrary website. You
will be redirected to the login URL of the RWTH computing center
(Rechenzentrum). Log on using:
◦ Login name: see printed version
◦ Password: see printed version
For more advanced technical assistance, please contact:
Uwe Kahlert
Room: 26C 411 (4th floor)
Tel: +49 241 80 27042
uwe@physik.rwth-aachen.de
8

Lunch information
Lunch will be taken at the Mensa Vitae, just 5 minutes away on foot.
Please follow the crowd as we go there at 12.30.
• Vouchers are available each day at the workshop registration desk in
front the lecture hall.
• Coffee after lunch: please note that at the lecture hall there will be
no coffee right after lunch. So if you need coffee, please get it at the
Lavazza counter in the Mensa Vitae.
Lab-tour: on Tuesday you have the possibility of taking a tour through some
of the experimental labs in Aachen.
• Please register for this at the workshop registration table in front of
the lecture hall.
• We will serve a few sandwiches for lunch (30 min) and start the tour
with 4 locations immediately afterward:
◦ 13:00 Sub-k scanning tunneling microscope (Morgenstern)
◦ 13:15 Spin-qubits (Bluhm)
◦ 13:30 Quantum-transport graphene nanostructures (Stampfer)
◦ 13:45 Time-resolved optics for spintronics (Beschoten)
◦ 14:00 Workshop continues
9

Conference dinner
The conference dinner will take place on
Tuesday evening 19:30
at the Ratskeller, located on the square in the old city center:
To get there,
Ratskeller Aachen
Markt 40
52062 Aachen
Tel. 0241-35001
http://www.ratskeller-aachen.de
• Exit the institute using the main access tower 26 (at the side of the
parking lots) and cross the street.
• Take Bus 3B and get out at Ponttor, an old city gate.
• Just walk down the Pontstrasse until you find yourself at the square
After dinner: Many student pubs can be found in the Pontstrasse that you
walked through above....
10

Talks Monday February 4
Talk program & abstracts
Talks Monday February 4
Monday (Feb. 4)
8:45 Opening
9:00 Herre van der Zant
Transport through individual magnetic molecules
9:45 Sander Otte
Atomically assembled quantum spin lattices
10:30 Coffee break
11:00 Ireneusz Weymann
Interplay of the Kondo effect and spin-polarized transport
in magnetic molecules, adatoms, and quantum dots
11:45 Jens Paaske
Fine structure in cotunneling spectroscopy
12:30 Lunch
14:00 Carsten Timm
The master equation for nanoscopic transport:
Spectral analysis, perturbation theory,
and applications to molecular devices
14:45 Jürgen König
Superconducting proximity effect in quantum-dot systems
15:30 Poster session
17:00 Stefan Heinze
Spontaneous atomic-scale magnetic skyrmion lattice
in an ultra-thin film
17:45 Achim Rosch
Magnetic whirls in chiral magnets
18:30
11

Talks Monday February 4
Transport through individual magnetic molecules
Herre van der Zant, Kavli Institute of Nanoscience Delft, The Netherlands
By merging the fields of molecular magnetism, molecular electronics and
nanotechnology, we fabricate planar three-terminal nanodevices containing
individual magnetic molecules or nanoparticles. Source and drain electrodes
are made of Au or of (multi-layered) graphene. A third gate electrode allows
the modification of charge transport independently from the source/drain
electrodes. In this way, a spin transistor is built in which the electric current
through the individual magnetic molecule or nanoparticle is sensitive to its
spin properties. The molecular complexes of interest are single-molecule magnets
(SMMs) and spin-crossover compounds. Coulomb blockade is generally
observed but finer details such as Kondo correlations and excited states are
observed at cryogenic temperatures [1]. In a Fe-4 SMM based transistor, we
observe features that confirm the high-spin state and find Kondo behavior,
spin blockade and a zero-field splitting that depends on the redox state; in
the charged state the molecule turns out to be a better magnet. Using an
in-situ sample rotator, direct observation of magnetic anisotropy has been
demonstrated [3]. Recent progress includes transport through a single spincrossover
molecule [4] and the fabrication of a molecular memory device based
on a spin-crossover nanoparticle that operates near room temperature [5].
Interestingly for molecular spintronics, the spin crossover in these devices
can be induced by applying a voltage, showing that its magnetic state is
controllable electrically.
Work supported by FOM and through the EU FP7 program (ELFOS)
[1] H.B. Heersche et al., Rev. Lett. 96 (2006) 206801; E.A. Osorio et al.,
Nano Letters 10 (2010) 105; J.M. Thijssen and H.S.J. van der Zant, Phys.
stat. sol. (b) 245 (2008) 1455-1470.
[2] A. Zyazin et al. Nano Letters 10 (2010) 3307.
[3] E. Burzurí, A.S. Zyazin, A. Cornia and H.S.J. van der Zant, Phys. Rev.
Lett. 109 (2012) 147203.
[4] V. Meded et al., Phys. Rev. B 83 (2011) 245115.
[5] F. Prins et al. Adv. Mat. 23 (2011) 1545.
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Talks Monday February 4
Notes
13

Talks Monday February 4
Atomically assembled quantum spin lattices
Sander Otte, Kavli Institute of Nanoscience Delft, The Netherlands
The physical behavior of lattices consisting of coupled quantum spins is often
hard to predict, even when only few spins are involved. Yet, insight into such
basic lattices can be key towards understanding the fascinating properties of
complex magnetic materials on the macroscopic scale.
In our lab we study small one- and two-dimensional lattices of magnetic
atoms by building them from scratch, literally atom-by-atom, using low temperature
scanning tunneling microscopy. Once built, the atomic structures
can be probed locally using a combination of inelastic electron tunneling
spectroscopy (IETS) and spin-polarized STM.
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Talks Monday February 4
Notes
15

Talks Monday February 4
Interplay of the Kondo Effect and Spin-Polarized Transport in Magnetic
Molecules, Adatoms, and Quantum Dots
Ireneusz Weymann, Adam Mickiewicz University, Poznań
Theoretical results on the interplay of the Kondo effect and spin-polarized
tunneling in a class of systems exhibiting uniaxial magnetic anisotropy, such
as magnetic molecules, magnetic adatoms, or quantum dots coupled to a
localized magnetic moment will be presented. In particular, the dependence
of the spectral functions and linear conductance on the system’s parameters
will be thoroughly discussed. It will be shown that both the magnetic
anisotropy as well as the exchange coupling between electrons tunneling
through the conducting orbital and magnetic core play an important role
in the formation of the Kondo resonance, leading generally to its suppression.
Specific transport properties of such a system appear also as a nontrivial
behavior of tunnel magneto-resistance. Moreover, the underscreened Kondo
effect in spin S=1 magnetic quantum dots will be discussed.
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Talks Monday February 4
Notes
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Talks Monday February 4
Fine structure in cotunneling spectroscopy
Jens Paaske, University of Copenhagen, Denmark
Cotunneling through Coulomb blockaded nano-transistors provides an informative
spectroscopy of the system bridging source and drain contacts. In this
talk, I address the question to what extent this transport probe can also tell
us more about the spin-orbit coupling in the dot, tube, wire or molecule under
scrutiny. From inelastic cotunneling spectroscopy, one might directly observe
avoided crossings between spin-orbit coupled states, but there are also a
number of more subtle clues to be picked up. What happens to the Kondo
resonances, reflecting the “flippable” degeneracies in the system, what are the
effects on tunneling induced level renormalization, and to what extent have
we already observed some of this spectroscopic fine structure experimentally?
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Talks Monday February 4
Notes
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Talks Monday February 4
The master equation for nanoscopic transport: Spectral analysis, perturbation
theory, and applications to molecular devices
Carsten Timm, Technische Universität Dresden, Germany
The master equation is a powerful method for the description of nanostructures
with strong interactions far from equilibrium. Using a master equation
for a molecular device coupled to a vibrational mode as an example, I will
analyze what information can be gained from the spectrum of eigenvalues
of the transition-rate matrix. So far, research has mostly focused on the
stationary state, which is the eigenstate to the (usually unique) vanishing
eigenvalue of this matrix. I will show that its full spectrum and its slowly
decaying eigenstates give useful information on the dynamics and are characteristic
of various regimes, such as the Coulomb and the Franck-Condon
blockade. In practice, the master equation is usually combined with perturbation
theory in the hybridization between the nanostructure and the electronic
leads. I will discuss recent theoretical progress regarding the exact time-convolutionless
(time-local) master equation to all orders in the hybridization.
Finally, I will comment on applications of the master equation to molecular
devices, including the direct comparison with break-junction experiments.
20

Talks Monday February 4
Notes
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Talks Monday February 4
Superconducting Proximity Effect in Quantum-Dot Systems
Jürgen König, University of Duisburg-Essen, Germany
We theoretically analyze electronic transport through interacting quantum
dots tunnel coupled to normal and superconducting leads. The proximity of
superconducting leads induces superconducting correlations in the quantum
dot which mediate Josephson and Andreev currents through the dot. Based
on a real-time diagrammatic approach formalism, we address non-local
Andreev effects in single- and double dot geometries and discuss the possibility
to induce unconventional (e.g. odd-triplet) pairing amplitudes.
22

Talks Monday February 4
Notes
23

Talks Monday February 4
Spontaneous atomic-scale magnetic skyrmion lattice in an ultra-thin film
Stefan Heinze, University of Kiel, Germany
Skyrmions are topologically protected field configurations with particle-like
properties that play an important role in various fields of science [1]. In
the context of magnetism, they have been predicted to form stable phases
and, recently, experimental evidence for their existence has been found for
bulk materials in a certain range of temperature and magnetic field [2,3]. A
very important ingredient for their occurrence is the Dzyaloshinskii-Moriya
interaction (DMI) which was recently found to be strong also in ultrathin
magnetic films on substrates with large spin-orbit coupling [4]. In these systems
the DMI induces spin-spirals with a unique rotational sense propagating
along one direction of the surface as observed for ultra-thin films [4-6] and
atomic chains [7]. The latter case is a prototypical system in which the
hybridization between the 3d-transition-metal chains (Fe) hybridize strongly
with the heavy 5d-transition-metal substrate (Ir) which leads to a weak
Heisenberg exchange interaction and a dominant DMI. Here, we go a step
beyond and present an atomic-scale magnetic skyrmion lattice for a hexagonal
Fe monolayer on the Ir(111) surface [8]. We develop a spin-model
based on density functional theory that explains the interplay of Heisenberg
exchange, DM interaction and the four-spin exchange as the microscopic
origin of this intriguing magnetic state. Experiments using spin-polarized
scanning tunneling microscopy confirm the skyrmion lattice which is incommensurate
with the underlying atomic lattice.
This work is a collaboration with G. Bihlmayer, S. Blügel, K. von Bergmann,
M. Menzel, A. Kubetzka, J. Brede, and R. Wiesendanger.
[1] T. H. Skyrme, Proc. R. Soc. Lond. Ser. A 260, 127 (1961).
[2] S. Mühlbauer et al., Science 323, 915 (2009).
[3] X. Z. Yu et al., Nature 465, 901 (2010).
[4] M. Bode et al., Nature 447, 190 (2007).
[5] P. Ferriani et al., Phys. Rev. Lett. 101, 027201 (2008).
[6] Y. Yoshida et al., Phys. Rev. Lett. 108, 087205 (2012).
[7] M. Menzel et al., Phys. Rev. Lett. 108, 197204 (2012).
[8] S. Heinze et al., Nature Phys. 7, 713 (2011).
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Talks Monday February 4
Notes
25

Talks Monday February 4
Magnetic Whirls in Chiral Magnets
Achim Rosch, University of Cologne, Germany
In cubic magnets without inversion symmetry, lattices of magnetic whirls, socalled
skyrmions are stabilized by spin-orbit interactions and thermal fluctuations.
The coupling of these magnetic whirls to electrons can be described
by emergent electric and magnetic field. This coupling is very efficient and
allows to move the skyrmions by ultrasmall current densities. The emergent
fields can be used to detect the presence and motion of the skyrmions. We also
discuss how such skyrmion phases can be created and destroyed by changing
the topology of the magnetic structure.
26

Talks Monday February 4
Notes
27

Talks Tuesday February 5
28

Talks Tuesday February 5
Talks Tuesday February 5
Tuesday (Feb. 5)
9:00 Hartmut Buhmann
Mercury telluride, a topological insulator
9:45 Henrik Johannesson
Electrical control of the Kondo effect in a helical edge liquid
10:30 Coffee break
11:00 Mircea Trif
Resonantly tunable Majorana polariton in a microwave cavity
11:45 Piet Brouwer
Subgap states in Majorana wires
12:30 Lunch + labtour (requires registration)
14:00 Vlad Pribiag
Spin-orbit-mediated control of electron
and hole spins in InSb nanowire quantum dots
14:45 Reinhold Egger
Majorana single-charge transistor
15:30 Poster session
17:00 Silvano De Franceschi
Tunnel spectroscopy of hybrid quantum dots
17:45 Seigo Tarucha
Generation and detection of quantum coherence
and entanglement with quantum dots
18:30
19:30 Conference dinner
29

Talks Tuesday February 5
Mercury Telluride, A Topological Insulator
Hartmut Buhmann, University Würzburg, Germany
The increasing understanding of topological phases in condensed matter
physics, which was initiated by the quantum Hall effect, has inspired the
search for further topological states, especially, in the absence of magnetic
fields. As an example a new topological insulator state, the quantum spin
Hall (QSH) effect, was proposed for two-dimensional electron system with
strong spin-orbit coupling [1,2] This new state is characterized by an insulating
bulk and two counter-propagating helical edge states, which give rise
for quantized conductance and propagating spin currents without dissipation.
After the successful experimental demonstration of the QSH effect [3],
the concept of topological insulators was extended to three-dimensional systems
[4] where two-dimensional Dirac-like surface states dominate electronic
and optical excitations resulting in new exotic properties.
In this presentation, the material system of mercury-telluride (HgTe) is
introduced. The realization of transport experiments in a two-dimensional
topological insulator (TI) state is shown [5,6,7] which demonstrates the
potential of the QSH effect for spin injection and detection in spintronics
applications. Recently, the three-dimensional TI state has been realized in
strained HgTe bulk layers [8]. The magneto-transport data show characteristic
Hall-sequences of two independent 2D Dirac surfaces.
1) C.L. Kane and E.J. Mele, Phys. Rev. Lett 95, 226801 (2005).
2) B.A. Bernevig and S.C. Zhang, Phys. Rev. Lett. 96, 106802 (2006).
3) M. König et al., Science 318, 766 (2007).
4) L. Fu and C.L. Kane, Phys. Rev. B 76, 045302 (2007).
5) M. König et al. Journ. Phys. Soc. Japn. 77, 031007 (2008).
6) A. Roth et al., Science 325, 294 (2009).
7) C. Brüne et al., Nature Physics 8, 485 (2012).
8) C. Brüne et al., Phys. Rev. Lett. 106, 126803 (2011).
30

Talks Tuesday February 5
Notes
31

Talks Tuesday February 5
Electrical control of the Kondo effect in a helical edge liquid
Henrik Johannesson, University of Gothenburg, Sweden
Magnetic impurities affect the transport properties of the helical edge states
of quantum spin Hall insulators by causing single-electron backscattering.
We study such a system in the presence of a Rashba spin-orbit interaction
induced by an external electric field, showing that this can be used to control
the Kondo temperature, as well as the correction to the conductance due to
the impurity. Surprisingly, for a strongly anisotropic electron-impurity spin
exchange, Kondo screening may get obstructed by the presence of a noncollinear
spin interaction mediated by the Rashba coupling. This challenges
the expectation that the Kondo effect is stable against time-reversal invariant
perturbations.
32

Talks Tuesday February 5
Notes
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Talks Tuesday February 5
Resonantly Tunable Majorana Polariton in a Microwave Cavity
Mircea Trif, UCLA, USA
We study the spectrum of a one-dimensional Kitaev chain placed in a
microwave cavity. In the o-resonant regime, the frequency shift of the cavity
can be used to identify the topological phase transition of the coupled system.
In the resonant regime, the topology of the system is sensitive to the presence
of photons in the microwave cavity and, moreover, for a large number
of photons (classical limit), the physics becomes similar to that of periodically-driven
systems (Floquet insulators). We also analyze numerically a
finite chain and show the existence of a degenerate subspace in the presence
of the cavity that can be interpreted as a Majorana polariton.
34

Talks Tuesday February 5
Notes
35

Talks Tuesday February 5
Subgap states in Majorana wires
Piet Brouwer, Freie Universität Berlin, Germany
A one-dimensional spin-orbit coupled nanowire with proximity-induced
pairing from a nearby s-wave superconductor may be in a topological nontrivial
state, in which it has a zero energy Majorana bound state at each end.
In this talk, I will discuss how non-idealities in this proposal, such as disorder
or deviations from a strict one-dimensional limit, affect the topological phase.
36

Talks Tuesday February 5
Notes
37

Talks Tuesday February 5
Spin-orbit-mediated control of electron and hole spins in InSb nanowire
quantum dots
Vlad Pribiag, Kavli Institute of Nanoscience Delft, The Netherlands
The spin-orbit interaction allows fast control of individual spins in quantum dots
using electric fields. Narrow-gap III-V semiconductor nanowires (InAs and InSb)
exhibit strong spin-orbit coupling, which makes them a promising platform for spinbased
qubits [1,2]. In this talk I will focus on InSb nanowires, which are of high
interest both for qubits and for observing Majorana fermions.
Using electric-dipole spin resonance (EDSR) we demonstrate coherent and universal
control over the spin-orbit eigenstates of individual electrons, with Rabi
frequencies in excess of 100 MHz and estimated fidelities of ∼ 81%. The large
Zeeman energy difference between adjacent dots enables selective addressing of each
qubit. Furthermore, we use EDSR in the strong interdot coupling regime to probe
the strength and anisotropy of the spin-orbit coupling. The data in agreement with
Rashba spin-orbit coupling, with α∼ 0.23 eVÅ. Although the Rabi oscillations for
InSb nanowire qubits are considerably faster than for GaAs qubits, the coherence
times are relatively short (Techo ∼ 35 ns) and show no significant dependence on
driving frequency within the accessible range of 8-32 GHz. This is consistent with
dephasing due to a fast spin bath that likely originates from the large nuclear spins
of InSb (5/2 and 7/2 for 121Sb and 123Sb respectively, and 9/2 for In).
A promising approach to enhancing qubit coherence is to use hole spins as qubits
instead of electron spins because hole spins exhibit weaker hyperfine coupling [3].
Taking advantage of the small bandgap of InSb, we can readily gate-tune our
nanowire devices between few-electron and few-hole quantum dots [4]. Comparison
between the two regimes suggests that the holes are primarily of light character and
that the hyperfine interaction is about an order of magnitude weaker for holes than
for electrons. We demonstrate rotation of hole spin states via EDSR and use this
to extract the hole g-factor, which is about an order of magnitude smaller than for
electrons. We compare the anisotropies of the g-factor and spin blockade leakage
current for holes and electrons. The ability to control and read out hole spin states
paves the way for coherent, all-electrical hole-spin qubits.
[1] C. Flindt, A. S. Sørensen, K. Flensberg, Phys. Rev. Lett. 97 240501 (2006).
[2] S. Nadj-Perge, S. M. Frolov, E. P. A. M. Bakkers, and L. P. Kouwenhoven,
Nature 468, 1084 (2010).
[3] D. Brunner, B. D. Gerardot, P. A. Dalgarno, G. Wüst, K. Karrai, N. G. Stoltz,
P. M. Petroff, R. J. Warburton, Science 325, 70 (2009).
[4] V. S. Pribiag, S. Nadj-Perge, S. M. Frolov, J. van den Berg, I. van Weperen,
S. R. Plissard, E. P. A. M. Bakkers, and L. P. Kouwenhoven, Submitted.
38

Talks Tuesday February 5
Notes
39

Talks Tuesday February 5
Majorana single-charge transistor
Reinhold Egger, Heinrich-Heine-Universität Düsseldorf, Germany
I discuss quantum transport properties through a topological insulator
nanowire with proximity-induced pairing correlations, where Majorana
fermions are present at the ends as a consequence of strong spin-orbit interactions.
When contacted by normal leads, and taking into account the charging
energy, this Majorana single-charge transistor allows to study Majorana
physics in a well-defined and relatively simple interacting model.
40

Talks Tuesday February 5
Notes
41

Talks Tuesday February 5
Tunnel spectroscopy of hybrid quantum dots
Silvano De Franceschi, CEA, Grenoble, France
Creating direct electrical connections between metal electrodes and lowdimensional
semiconductor nanostructures has recently become possible
thanks to the development of new nanomaterials and nanofabrication
methods. Hybrid devices can thus be made in which macroscopic properties,
such as superconductivity or ferromagnetism, are combined with microscopic
properties, such as the charge or the spin state of individual electrons. Such
hybrid devices open a wide range of opportunities for the study of new
quantum phenomena and, in the long term, they may lead to the development
of useful electronic devices with quantum functionalities.
In this talk I will focus on hybrid devices made of zero-dimensional, quantumdot
structures coupled to either normal or superconducting electrodes. I will
present recent results obtained with hybrid devices made from self-assembled
SiGe nanocrystals and InAs-based nanowires. Special attention will be
devoted to the magnetic properties of the confined states in both normal and
superconducting regime.
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Talks Tuesday February 5
Notes
43

Talks Tuesday February 5
Generation and Detection of Quantum Coherence and Entanglement with
Quantum Dots
Seigo Tarucha, University of Tokyo, Japan
Generation and detection of quantum coherence and entanglement is the core
of quantum information processing. In this talk I will discuss new approaches
to manipulate these concepts for electrons in semiconductor nanostructures.
We have recently developed a two-path interferometer consisting of an
Aharonov-Bohm ring connected to two tunnel-coupled quantum wires [1].
Conventional AB rings are connected to two terminals and therefore suffer
from phase rigidity which fixes the phase of AB oscillations at either 0 or
π at zero-magnetic field. On the other hand, our interferometer operating
in the non-adiabatic transport through the tunnel coupled wire does not
suffer from the phase rigidity. We electrically control the dynamical phase
through the AB ring and apply this technique to achieve full electrical control
of a flying charge qubit defined by the presence of electron in either
part of the two paths. We also use a similar interferometer but having a
quantum dot in one of the two AB ring arms to detect the transport phase
through the dot. We observe a well-defined π/2 phase through the dot when
the dot is in the Kondo regime.
The concept of non-local entanglement is well established for correlated
photon pairs, but not yet for electrons in solid state systems. We have
studied non-local entanglement using double dot Josephson junctions. The
splitting of Cooper pairs into both dots may contribute to generate supercurrent,
because Cooper pair tunneling through the same dot is strongly
suppressed by the electron-electron interaction [2]. We observe the supercurrent
depending on the double dot charge state and discuss the contribution
from the split Cooper pair tunneling to the supercurrent.
[1] M. Yamamoto et al. Nature Nanotechnology, 7, 247 (2012).
[2] Y. Kanai et al. Appl. Phys. Lett. 100, 202109 (2012).
44

Talks Tuesday February 5
Notes
45

Talks Tuesday February 5
46

Talks Wednesday February 6
Talks Wednesday February 6
Wednesday (Feb. 6)
9:00 Christian Schönenberger
Interference and interaction in ultraclean
suspended monolayer and bilayer graphene
9:45 Bernd Braunecker
Spin-orbit interaction in carbon nanotubes
and its utility for proving entanglement of electrons
10:30 Coffee break
11:00 Kasper Grove-Rasmussen
Level structure and tunnel coupling of carbon nanotube quantum dots
11:45 Charlie Marcus
(to be announced)
12:30 Lunch
Talks of the Research Unit
Coherence and Relaxation Properties of Electron Spins
All participants of the workshop are invited.
14:00 Y. Mokrousov
Engineering Chern insulators with spin and orbital degrees of freedom
14:25 R. Steinigeweg
Real-time dynamics of spin-currents in quantum magnets:
Coherence and momentum dependence
14:50 V. Kataev
ESR spectroscopy on spin-orbital Mott insulators
15:15 S. Müller
Magnetic field effects on the finite-frequency noise
and ac conductance of a Kondo quantum dot out of equilibrium
15:40 B. Büchner
Quasi-ballistic transport of Dirac fermions in Bi2Se3 nanowires
16:05 Coffee break
16:30 I. Stepanov
Spintronics without ferromagnets
16:55 C. Honerkamp
Interacting ground states of few-layer graphene
17:10 B. Beschoten
Spin transport in graphene
17:35 C. Volk
Probing relaxation times in graphene quantum dots
18:05 P. Struck
Nanomechanical read-out of a single spin
18:20 End of the workshop
47

Talks Wednesday February 6
Interference and interaction in ultraclean suspended monolayer and bilayer
graphene
Christian Schönenberger, University of Basel, Switzerland
We first show that graphene (monolayer and bilayer) with exceptional high
mobilities approaching 100 m 2 /Vs can be obtained when suspended and insitu
current annealed. Using such materials, we then first summarize recent
results obtained with bilayer graphene where a pronounced gap emerges at
the charge-neutrality point. This gap forms in zero electric and magnetic field
and is thought to be accompanied by a transition into a broken symmetry
state. The precise nature of this ground state is currently debated. We show
that our results are consistent with both the layer anti-ferromagnetic state
(LAF) and the quantum-spin Hall state (QSH). While we cannot distinguish
these two states, we can exclude the quantum anomalous Halls state based
on electrical measurements in parallel magnetic field.
We further will demonstrate electrical transport experiments in monolayer
graphene with top gates arranged in the form of strips. The gates allow to
define n-p regions yielding a peculiar interference pattern in high mobility
samples caused by Klein tunneling.
Coauthors:
Frank Freitag, Peter Rickhaus, Romain Maurand, Jelena Trbovic, Markus
Weiss and Christian Schönenberger
48

Talks Wednesday February 6
Notes
49

Talks Wednesday February 6
Spin-orbit interaction in carbon nanotubes and its utility for proving entanglement
of electrons
Bernd Braunecker, Universidad Autónoma de Madrid, Spain
I will discuss spin-orbit interaction in carbon nanotubes and show that it
has distinct features that allow to obtain information on the entanglement of
injected pairs of electrons. I will briefly review the form of spin-orbit interaction
in single-wall nanotubes, and demonstrate that it leads to a perfect
spin filter with spin orientations that are tunable by external fields. Based on
this, I will focus on a Cooper pair splitter setup and show that the tunable
spin-filtering allows to implement entanglement detectors, such as probing a
Bell inequality. These detectors can rely on conductance measurements alone
and do not require the precise knowledge of the spin orientations of the spin
filter. Yet if in addition the spin orientations are known, the same setup can
be used for full quantum state tomography.
50

Talks Wednesday February 6
Notes
51

Talks Wednesday February 6
Level structure and tunnel coupling of carbon nanotube quantum dots
Kasper Grove-Rasmussen, University of Copenhagen, Denmark
We present our current understanding of the quantum states in a carbon
nanotube quantum dot deduced from low temperature transport measurements
in parallel and perpendicular magnetic fields. The observed energy
spectrum is shown to be ordered in shells of two doublets consistent with a
single-particle four-state model including spin-orbit interaction, intra-shell
valley mixing and an orbital g-factor. To fully capture the behavior in the
multi-shell case, additional inter-shell valley mixing parameters are needed,
describing valley mixing between states belonging to different shells [1, 2].
Furthermore, for certain shells, the two doublets are observed to be differently
coupled to the leads, resulting in gate-dependent level renormalization.
By comparison to the one-shell model this is shown to be a consequence
of intra-shell valley mixing in the nanotube. Moreover, a parallel magnetic
field is shown to reduce this mixing and thus suppress the effects of tunnelrenormalization
[3].
[1] T. Sand Jespersen, K. Grove-Rasmussen, J. Paaske, K. Muraki, T. Fujisawa,
J. Nygård, and K. Flensberg, Nat. Phys. 7, 348 (2011).
[2] T. S. Jespersen, K. Grove-Rasmussen, K. Flensberg, J. Paaske, K.
Muraki, T. Fujisawa, and J. Nygård, Phys. Rev. Lett. 107, 186802 (2011)
[3] K. Grove-Rasmussen, S. Grap, J. Paaske, K. Flensberg, S. Andergassen,
V. Meden, H. I. Jørgensen, K. Muraki, and T. Fujisawa, Phys. Rev. Lett.
108, 176802 (2012).
52

Talks Wednesday February 6
Notes
53

Talks Wednesday February 6
(to be announced)
Charles Marcus, University of Copenhagen, Denmark
(to be announced)
54

Talks Wednesday February 6
Notes
55

Posters Monday February 4
Poster program & abstracts
Posters Monday February 4
Time: 15:30 - 17:00
Poster numbers: 1-20
Topics:
Atomic and molecular scale devices
Semiconductor quantum dots and wires
57

Posters Monday February 4
Poster 1:
Dynamical spin and charge excitations with spin–orbit coupling in 3d adatoms
on Cu(111) and Pt(111)
Manuel dos Santos Dias
The presence of spin–orbit coupling has a fundamental impact on the
magnetic excitation spectrum: there is a finite gap at zero frequency and
spin and charge excitations become coupled. The excitation spectrum is
derived from the dynamical magnetic susceptibility of the electronic system,
for which we developed a formalism based on Time–Dependent Density
Functional Theory, as implemented in the Korringa–Kohn–Rostoker Green
function method [1,2]. As an application, we present first–principles calculations
of the charge, longitudinal and transverse magnetic excitations of
3d adatoms deposited on the Cu(111) and Pt(111) surfaces. Focus is on
the expected spin–charge coupling induced by the the spin–orbit interaction,
and on the dynamical anisotropic effects that generalize the familiar
magnetic anisotropy.
Work supported by the HGF-YIG Programme FunSiLab – Functional
Nanoscale Structure Probe and Simulation Laboratory (VH-NG-717).
[1] S. Lounis, A. T. Costa, R. B. Muniz and D. L. Mills, Phys. Rev. Lett.
105, 187205 (2010)
[2] S. Lounis, A. T. Costa, R. B. Muniz and D. L. Mills, Phys. Rev. B 83,
035109 (2011)
58

Posters Monday February 4
Poster 2:
Spintronic molecular magnetism: zero field splitting without spin-orbit coupling
Michael Hell
Single-molecule magnets (SMMs) and magnetic adatoms have been studied
intensely mainly because of their large spin anisotropy. In these systems,
a spin-anisotropy barrier arises from internal quantum fluctuations due to
strong spin-orbit interaction. However, such a spin-anisotropy barrier can
also be externally induced into an intrinsically spin-isotropic system by coupling
it to an spin-anisotropic environment.
We illustrate this new idea for an interacting quantum dot (QD) with a high
spin S>1/2, tunnel-coupled to spin-polarized electrodes. Besides dissipative
effects, multi-spin currents generate an additional coherent time evolution
of the QD, which is described by an effective Hamiltonian. The latter contains
the dipolar exchange field [1-3], well known from spintronics, and an
additional, new exchange field coupling to the spin-quadrupole moment of
the QD. This spintronic spin-anisotropy barrier can be comparable in size to
that of SMMs, but grants the additional flexibility of electric and magnetic
tunability.
We compare these analytic results, obtained by a perturbative treatment
of the tunnel-couplings, to predictions by DM-NRG calculations accessing
the strong coupling regime. We show that transport characteristics can be
used to directly read out the quadrupolar field, utilizing its competition
with Kondo spin-exchange processes with the ferromagnets. Furthermore,
the quadrupolar exchange field can dominate over the dipolar exchange field,
thereby strongly enhancing the low-temperature spin-filtering as compared
to spin-1/2 QD spin-valves.
References:
[1] J. Martinek et al., Phys. Rev. Lett. 91, 127203 (2003); Phys. Rev. B 72,
121302 (2005).
[2] J. Hauptmann et al., Nature Phys. 4, 373 (2008).
[3] M. Gaass et al., Phys. Rev Lett. 107, 176808 (2011).
[4] M. Baumgärtel et al., Phys. Rev. Lett. 107, 087202 (2011)
Coauthors
M. Misiorny and M. R. Wegewijs
59

Posters Monday February 4
Poster 3:
Influence of magnetic anisotropy on the underscreened Kondo effect in the
presence of ferromagnetism
Maciej Misiorny
The prominent role of magnetic anisotropy (MA) in formation of the Kondo
effect has recently been demonstrated experimentally [1,2]. In particular, it
turned out that in systems of spin S>1/2, such as magnetic adatoms (i.e.
Fe, Co or Mn) or magnetic molecules, the Kondo effect can be tuned by
modifying the system’s MA. Furthermore, theoretical studies also indicate
that MA can be a key factor determining spin-polarized transport through
a magnetic nanosystem [3]. Motivated by the recent experiment [2], in this
communication we address how the MA affects the underscreened Kondo
effect (i.e. partial compensation of the molecular spin by conduction electrons)
in the case of an artificial molecule of spin S=1 coupled to a reservoir
of spin-polarized conduction electrons [4]. The crucial ingredient of the model
is the presence of uniaxial MA. The problem is analyzed by means of Wilson’s
numerical renormalization group (NRG) method, which allows for calculating
the spectral function of the molecule. We show that the interplay of MA and
ferromagnetism has a fundamental significance for occurring of the Kondo
effect. Most importantly, despite the presence of the effective exchange field
[5] the Kondo effect can be restored by adjusting the magnitude of MA.
1. A.F. Otte et al., Nature Phys. 4, 847 (2008).
2. J.J. Parks et al., Science 328, 1370 (2010).
3. M. Misiorny, I. Weymann and J. Barnas, Phys. Rev. Lett. 106, 126602
(2011); Phys. Rev. B 84, 035445 (2011).
4. I. Weymann and L. Borda, Phys. Rev. B 81, 115445 (2010).
5. J. Martinek et al., Phys. Rev. Lett. 91, 127203 (2003); Phys. Rev. B 72,
121302 (2005).
Coauthors
I. Weymann and J. Barnaś
60

Posters Monday February 4
Poster 4:
Kondo effect and magnetic frustration in a system of magnetic trimer on a
metal surface
Hoa Nghiem
We use quantum Monte Carlo simulation to clarify the competition between
Kondo screening and magnetic frustration in a system of three magnetic
adatoms on a metal surface [1]. We observe the feature of spectral density
depending on the geometric configuration of three magnetic adatoms on the
surface [2, 3]. In the isosceles configuration, the spectral density exhibits a
significant peak near the Fermi level, which we attribute to the Yosida-Kondo
resonance. In the equilateral configuration, no peak is observed near the
Fermi level. This observation suggests the two separate regimes; the Yosida-
Kondo dominant regime with the singlet ground state, and the magnetic
frustration dominant regime with the degenerate ground state, - changing
from one regime to another is realized as we gradually switch the geometric
configuration from the isosceles triangle to equilateral one. By calculating
the spectral density and the magnetic susceptibility in a wide range of temperatures,
we prove the existence of the two separate regimes and suggest
the critical crossover between them.
[1] N. T. M. Hoa, W. A. Dino, and H. Kasai: J. Phys. Soc. Jpn. 81 (2012)
023706.
[2] T. Jamneala, V. Madhavan, and M. F. Crommie: Phys. Rev. Lett 87
(2001) 256804.
[3] N. T. M. Hoa, W. A. Dino, and H. Kasai: J. Phys. Soc. Jpn. 79 (2010)
113706.
Poster 5:
Spin dynamics in nanoparticles near Stoner instability
Philipp Stegmann
We analyse the spin dynamics of a nanoparticle close to the Stoner instability.
The nanoparticle is weakly tunnel coupled to two ferromagnetic leads. By
mapping to an effective Fokker-Planck description we identify two different
types of dynamic behaviour (diffusion vs. drift), which are revealed by characteristic
relaxation times and a Fano factor that oscillates as a function of an
applied bias voltage. Finally, we propose biasing schemes to generate states
with magnetic quadrupole moments that dominate over a negligible dipole
moment.
61

Posters Monday February 4
Poster 6:
Nonequilibrium transport through quantum dots with Dzyaloshinskii-Moriya
interactions
Mikhail Pletyukhov
We study nonequilibrium transport through a single-orbital Anderson
model in a magnetic field with spin-dependent hopping amplitudes. In
the cotunneling regime it is described by an effective spin-1/2 dot with a
Dzyaloshinsky-Moriya-Kondo (DMK) interaction between the spin on the
dot and the electron spins in the leads. Using a real-time renormalization
group technique we show that at low temperatures (i) the DMK interaction
is strongly renormalized, (ii) the renormalized magnetic field acquires a linear
voltage dependence, and (iii) the differential conductance exhibits a voltage
asymmetry which is strongly enhanced by logarithmic corrections. We propose
transport measurements in which these signatures can be observed.
62

Posters Monday February 4
Poster 7:
Spin-Orbit interactions and the Kondo effect
Nancy Sandler
Recent studies [1] have pointed out that the thermodynamics of the Kondo
effect are essentially unaltered by the presence of Rashba spin-orbit interactions
in a host two-dimensional electron gas. However, it has also been
proposed [2]that the presence of bulk Rashba interactions induces a coupling
between a magnetic impurity and conduction electrons with nonzero orbital
angular momentum about the impurity site. This coupling appears as a
combination of the standard Kondo exchange and the Dzyaloshinskii-Moriya
interaction that, in the appropriate regime, produces an exponential enhancement
of the Kondo temperature. In this work we review previous works and
present recent results obtained by using the numerical renormalization group.
In agreement with previous studies, we find only minor changes in the Kondo
temperature scale when the Rashba coupling is increased at fixed Fermi
energy. However, for fixed band filling, increasing the spin-orbit coupling can
move the Fermi energy near to a Van Hove singularity in the effective density
of states, leading to an exponential enhancement of the Kondo scale. Static
spin correlations confirm that the impurity couples to conduction channels
of nonzero orbital angular momentum. We also explore the effects of a magnetic
field applied in the plane of the host system and extend our results to
graphene systems.
[1] J. Malecki, J. Stat. Phys. 129, 741 (2007); R. Zitko and J. Bonca, Phys.
Rev. B 84, 193411 (2011).
[2] M. Zarea, S. Ulloa and N. Sandler, Phys. Rev. Lett. 108, 046601 (2012).
63

Posters Monday February 4
Poster 8:
Influence of Noise on the Exchange-Only Qubit
Sebastian Mehl
Spin qubits have attracted interest as one realization scheme to achieve
quantum computation in a solid state system. Encoding qubits into more
than one quantum dot has turned out to be experimentally very favorable.
When encoding a qubit into three quantum dots one can show that electrostatic
bias offers full control of the qubit. It generates tunable exchange
interactions between neighboring quantum dots. We present the influence
of noise on the exchange-only qubit and discuss coherence properties. We
especially point out how the definition of the qubit in the embedding Hilbert
space can lead to different coherence properties.
Poster 9:
Effect of many-body correlations on mesoscopic charge relaxation
Jonckheere Thibaut
We investigate nonperturbatively the charge relaxation resistance and
quantum capacitance in a coherent RC circuit in the strong-coupling regime.
We find that the many-body correlations break the universality in the charge
relaxation resistance: (i) The charge relaxation resistance has peaks at finite
frequencies Γ/ , where Γ is an effective level broadening, and (ii) the zerofrequency
resistance deviates from the universal value when the Zeeman splitting
is comparable to Γ. This behavior becomes even more prominent in
the Kondo regime. The observed features are ascribed to the generation
of particle-hole excitations in the contacts accomplished by spin-flip processes
in the dot.
64

Posters Monday February 4
Poster 10:
Interplay of Coulomb interaction and spin-orbit effects in multi-level quantum
dots
Stephan Grap
We study electron transport through a multi-level quantum dot with Rashba
spin-orbit interaction in the presence of local Coulomb repulsion. Motivated
by recent experiments, we compute the level splitting induced by the spinorbit
interaction at finite Zeeman fields B, which provides a measure of
the renormalized spin-orbit energy. This level splitting is responsible for
the suppression of the Kondo ridges at finite B characteristic for the multilevel
structure. In addition, the dependence of renormalized g-factors on
the relative orientation of the applied B field and the spin-orbit direction
following two different protocols used in experiments is investigated.
Poster 11:
Transport properties of a multichannel Kondo dot in a magnetic field
Christoph Hörig
We study the nonequilibrium transport through a multichannel Kondo
quantum dot in the presence of a magnetic field. We use the exact solution
of the two-loop renormalization group equation to derive analytical results
for the g-factor, the spin relaxation rates, the magnetization, and the differential
conductance. We show that the finite magnetization leads to a coupling
between the conduction channels which manifests itself in additional features
in the differential conductance.
65

Posters Monday February 4
Poster 12:
An alternative functional renormalization group approach to the single impurity
Anderson model
Michael Kinza
We present an alternative functional renormalization group (fRG) approach
to the single-impurity Anderson model at finite temperatures. Starting
with the exact self-energy and interaction vertex of a small system (’core’)
containing a correlated site, we switch on the hybridization with a noninteracting
bath in the fRG-flow and calculate spectra of the correlated site.
Different truncations of the RG-flow-equations and choices of the core are
compared and discussed. Furthermore we calculate the linear conductance
and the magnetic susceptibility as functions of temperature and interaction
strength. The signatures of Kondo physics arising in the flow are compared
with numerical renormalization group results.
Poster 13:
Conductance scaling in Kondo correlated quantum dots: role of level asymmetry
Lukas Merker
The low temperature electrical conductance through correlated quantum dots
provides a sensitive probe of the physics (e.g., of Fermi-liquid vs non-Fermiliquid
behavior) of such systems. Here, we investigate the role of level asymmetry
(gate voltage) and local Coulomb repulsion (charging energy) on the
low temperature and low field scaling properties of the linear conductance of a
quantum dot described by the single level Anderson impurity model. We use
the numerical renormalization group and renormalized perturbation theory
to quantify the regime of gate voltages and charging energies where universal
Kondo scaling may be observed and also quantify the deviations from this
universal behavior with increasing gate voltage away from the Kondo regime
and with decreasing charging energy. Our results could be a useful guide for
detailed experiments on conductance scaling in semiconductor and molecular
quantum dots exhibiting the Kondo effect.
Coauthors
T. A. Costi, E. Munoz, S. Kirchner
66

Posters Monday February 4
Poster 14:
Fermionic superoperators in application to non-linear transport: real-time
renormalization group, time-evolution and exact relations for Anderson
quantum dots.
Roman Saptsov
We introduced a new formalism of fermionic superoperators in Liouville-
Fock space to enable a real-time renormalization group analysis of the nonequilibrium
Anderson model in the stationary state. The RT-RG equations
were solved numerically including both 1- and 2- loop orders in the limit of
zero temperature and non-linear transport voltages where most standard theoretical
methods break down. We predict non-perturbative tunneling effects
in the transport stability diagram which can be measured experimentally.
Moreover, we found the exact functional form of the renormalized spectra of
the dot at any loop order. In the strong-interacting limit the method breaks
down as expected only at very small voltages on the order of the Kondo
temperature, which we illustrate by comparison with the Friedel sum rule.
For the time dependent non-interacting case with help of fermionic superoperators
we show that the perturbation expansion in tunnel coupling automatically
truncates at the second loop and discuss solutions in the Wide Band
Limit and beyond of it. We also discuss extension of our time-dependent
results to the weakly interacting case.
67

Posters Monday February 4
Poster 15:
Mechanism for Giant Thermopower in Negative-U Molecular Quantum Dots
Theo Costi
We investigate with the aid of numerical renormalization group techniques
the thermoelectric properties of a molecular quantum dot described by the
negative-U Anderson model. We show that the charge Kondo effect provides
a mechanism for enhanced thermoelectric power via a correlation-induced
asymmetry in the spectral function close to the Fermi level. We show that
this effect results in a dramatic enhancement of the Kondo-induced peak in
the thermopower of negative-U systems with Seebeck coefficients exceeding
50 µV/K over a wide range of gate voltages [1,2].
[1] S. Andergassen, T. A. Costi and V. Zlatic, Phys. Rev. B 84, 241107 (R)
(2011)
[2] T. A. Costi and V. Zlatic, Phys. Rev. Lett. {bf 108}, 36402 (2012); in
"New Materials for Thermoelectric Applications: Theory and Experiment",
ed. V. Zlatic and A. C. Hewson, ISBN 978-94-007-4983-2 (Springer, Berlin,
2012)
Coauthors: S. Andergassen and V. Zlatic
Poster 16:
Boltzmann-type approach to thermal drag in spin-1/2-ladder systems coupled
to phonons
Christian Bartsch
We quantitatively investigate the spin-phonon drag contributions to the
thermal conductivity of a two-leg-spin-1/2-ladder coupled to lattice vibrations
in a magnetoelastic way. By applying suitable transformations the
system is mapped onto a weakly interacting quantum gas model of bosonic
spin excitations (magnons) and phonons. We adequately construct a collision
term of a linear(ized) Boltzmann equation from the underlying quantum
dynamics by means of a pertinent projection operator technique. From the
Boltzmann equation we obtain concrete numerical values for the drag conductivity
and relate it to the individual thermal conductivities of magnons and
phonons for parameter ranges which are typical for certain material classes.
68

Posters Monday February 4
Poster 17:
Rashba spin-orbit interaction in a quantum wire superlattice
Sigurdur I. Erlingsson
We study the effects of a longitudinal periodic potential on a parabolic
quantum wire, and long quantum point contacts, defined in a two-dimensional
electron gas with Rashba spin-orbit interaction. For an infinite wire
superlattice we find that the energy gaps are shifted away from the usual
Bragg planes due to the Rashba spin-orbit interaction. We have also calculated
the charge conductance through a periodic potential of a finite length
via the nonequilibrium Green’s function method combined with the Landauer
formalism. We find dips in the conductance that correspond well to
the energy gaps of the infinite wire superlattice. From the infinite wire energy
dispersion, we derive an equation relating the location of the conductance
dips as a function of the Fermi energy to the Rashba spin-orbit coupling
strength. We propose that the strength of the Rashba spin-orbit interaction
can be extracted via a charge conductance measurement.
Poster 18:
Electronic states in a cylindrical nanowire in magnetic and electric fields
Andrei Manolescu
Single particle states of electrons situated on a closed cylindrical surface of
radius 30-100 nm are calculated. The length of the cylinder may be either
infinite or finite. In the presence of a magnetic field uniform in space, but perpendicular
to the longitudinal axis of the cylinder, the orbital effects depend
on the radial component of the magnetic field. For a sufficiently strong field,
when the magnetic length becomes comparable to the radius of the cylinder,
the orbital motion corresponds to closed cyclotron orbits in the regions with
strong radial field, but to open quasi one-dimensional snaking orbits in the
regions where the radial field vanishes and changes sign. The energy of the
cyclotron states increases with the magnetic field relatively to the energy of
the snaking states such that at high magnetic fields the electrons concentrate
around the snaking orbits. The spin of the electron is included via Zeeman
and Rashba spin-orbit effects. A uniform electric field perpendicular to the
cylinder is also considered, as being produced by a metallic electrode placed
near the cylinder. In this case the spin-orbit coupling becomes anisotropic.
Attempts to include Coulomb effects in the Hartree-Fock approximation are
discussed.
69

Posters Monday February 4
Poster 19:
Quantized conductance in InSb nanowires and electrical characterization of
branched InSb nanowires
Ilse van Weperen
Indium antimonide (InSb) nanowires have shown potential for creation of
topological superconducting and helical liquid states. We report on transport
measurements of single high-mobility indium antimonide nanowires and
branched InSb nanowires.
A novel growth mechanism allows two InSb nanowires to merge into a nano-
T or nanocross. Transport measurements of branched nanowires show characteristics
similar to that of single nanowires. Magnetoresistance measurements
of nanocrosses allow extraction of nanowire electron density.
A mean free path of ∼ 300 nm in InSb nanowires enables observation of
one-dimensional conductance channels at high (B > 2 T) magnetic fields.
Conductance quantization is studied as a function of magnetic field and bias
voltage, enabling extraction of an effective g-factor of ∼ 65 and a subband
spacing of ∼ 15 meV.
Poster 20:
Phase-Coherent Transport and Spin-Orbit Coupling in InAs Nanowires
Sebastian Heedt
We report on phase-coherent transport measurements on differently doped
InAs nanowires grown by selective area metalorganic vapor phase epitaxy.
The nanowires are contacted individually and the low-temperature electronic
transport properties are investigated for temperatures down to 30 mK and
magnetic fields up to 10 T. To this end, top-gates with high-k dielectrics are
prepared. At small current-bias the transport is phase-coherent and gives
us the opportunity to determine the phase-coherence length and the spin
relaxation length. The band profile and the carrier concentration of the
nanowires can be manipulated by the application of a gate voltage. An analytical
model for the low-field quantum conductivity correction is utilized
to quantify Rashba and Dresselhaus spin-orbit coupling effects. Nanowires
with different doping concentrations are investigated to gain information
on how the doping of the highly spin-orbit coupled InAs nanowires impacts
the spin-lifetime.
70

Posters Tuesday February 5
Posters Tuesday February 5
Time: 15:30 - 17:00
Poster numbers: 21-43
Topics:
Spin-orbit hybrid systems
Carbon nanotubes and graphene
71

Posters Tuesday February 5
Poster 21:
Optical Josephson radiation from a Majorana Josephson junction
Christoph Ohm
We consider a voltage-biased Josephson junction between two nanowires
hosting Majorana fermions which occur as topological protected zero-energy
excitations at the junction. We show that two Majorana fermions localized
at the junction, though being neutral excitations, interact with the electromagnetic
field and generate coherent radiation similar to the conventional
Josephson radiation in a voltage biased Josephson junction. Within a semiclassical
analysis of the light field, we find that the optical phase gets locked
to the superconducting phase difference and that the radiation is emitted
at half of the Josephson frequency. In order to confirm the coherence of
the radiation, we study correlations of the light emitted by two spatiallyseparated
junctions in a SQUID geometry taking into account decoherence
by spontaneous phase-switchings due to quasi-particle poisoning as well as
by thermal effects.
Poster 22:
Spin-flip excitations induced by time-dependent electric fields in surfaces with
strong spin-orbit interaction
Julen Ibanez
Heavy element surfaces have become an ideal testing ground for investigating
the nature and effects of the relativistic spin-orbit interaction in low
dimensional systems. In this work, we study spin-flip transitions between the
metallic surface states of the Pb/Ge(111) and the Rashba prototype Au(111)
surfaces. We calculate the spin-flip matrix elements following an approach
based on the interpolation of maximally localized Wannier functions. The
obtained results show that spin-flip absorptions are one order of magnitude
larger in Pb/Ge(111) than in Au(111), reaching a remarkable maximum of
6% absorption of the total irradiated light.
We find that the enhanced spin-flip contribution in Pb/Ge(111) is closely
connected to the behavior of the momentum dependent spin-polarization
associated to the surface states.
72

Posters Tuesday February 5
Poster 23:
Quantum Dots and Majorana Fermions
Martin Leijnse
Majorana fermions, particles which are their own anti-particles, may or may
not exist as elementary particles in nature. However, it was shown theoretically
a few years ago that they can appear as quasiparticle excitations in
certain condensed matter systems combining superconductivity, magnetism,
and strong spin-orbit coupling. This has quickly become one of the hottest
topics in mesoscopic physics research, partly because of the possibility to use
Majorana fermions for quantum information processing.
I will present work suggesting a new and perhaps easier way to generate
Majorana-like bound states in a double quantum dot system, where the dots
are tunnel coupled to each other via a superconductor. I will also show that
quantum dots can be used to do more accurate spectroscopy of Majorana
systems, and even to manipulate quantum information stored in Majoranabased
qubits.
Poster 24:
Disorder-induced topological phase transitions in a quasi-1D spinless p-wave
superconductor
Maria-Theresa Rieder
Topological phases and the surface states associated with them are known
to be robust against weak disorder and to break down at a critical disorder
strength. In this letter we show how disorder induces a series of topological
phase transitions in a spinless multichannel p-wave superconducting
wire. We find that the wire alternates between topologically trivial and nontrivial
phases as the induced superconductivity is increased in a perturbative
approach to the transverse coupling.
73

Posters Tuesday February 5
Poster 25:
Majorana modes and complex band structure of quantum wires
Llorens Serra
We describe Majorana edge states of a semi-infinite wire using the complex
band structure approach. In this method the edge state at a given energy is
built as a superposition of evanescent waves. It is shown that the superposition
can not always satisfy the required boundary condition, thus restricting
the existence of edge modes. We discuss purely 1D and 2D systems, focussing
in the latter case on the effect of the Rashba mixing term. We also review
recent results on the calculation of Majorana modes in finite systems and of
the linear transport within a coupled-channels model.
References:
[1] Majorana modes and complex band structure of quantum wires, L. Serra,
arXiv:1210.4817
[2] Transport through Majorana nanowires attached to normal leads, J.S.
Lim, R. Lopez and L. Serra, New J. Phys. 14, 083020 (2012).
[3] Magnetic field instability of Majorana modes in multiband semiconductor
wires, J.S. Lim, L. Serra, R. Lopez and R. Aguado, Phys. Rev. B 86,
121103(R) (2012).
74

Posters Tuesday February 5
Poster 26:
Interaction induced charge and spin pumping in non-linear transport through
a quantum dot
Hernan Calvo
We investigate charge and spin transport through an adiabatically driven,
strongly interacting quantum dot weakly coupled to two metallic contacts
with finite bias voltage. Within a kinetic/master equation approach we identify
coefficients of response to the time-dependent external driving and relate
these to the concepts of charge and spin emissivities in the time-dependent
scattering matrix approach. Expressed in terms of auxiliary vector fields the
response coefficients allow for a straightforward analysis of recently predicted
interaction-induced pumping under periodic modulation of the gate and bias
voltage [1]. We perform a detailed study of this effect and the related adiabatic
Coulomb blockade spectroscopy, and, in particular, extend it to spin
pumping. Analytic formulas for the pumped charge and spin in the regimes
of small and large driving amplitude are provided for arbitrary bias. In the
absence of a magnetic field, we obtain a striking, simple relation between
the pumped charge at zero bias and at bias equal to the Coulomb charging
energy. At finite magnetic field, interaction-induced pure spin pumping is
shown to be possible at this finite bias value, and additional features appear
in the pumped charge. For large-amplitude adiabatic driving, the magnitude
of both the pumped charge and spin at the various resonances saturate at
values which are independent of the specific shape of the pumping cycle.
Each of these values provide an independent, quantitative measurement of
the junction asymmetry.
75

Posters Tuesday February 5
Poster 27:
Adiabatic pumping through an interacting quantum dot with spin-orbit coupling
Stephan Rojek
We study adiabatic pumping through a two-level quantum dot coupled to two
normal metallic leads in the presence of spin-orbit coupling.[1] The variation
of the two energy levels of the dot periodically in time leads to finite charge
and spin currents.
We calculate the pumped charge and spin using a diagrammatic real-time
approach.[2] Going beyond the limit of noninteracting electrons on the
quantum dot,[3] we study the situation of strong Coulomb interaction. In
both limits of noninteracting and strongly interacting electrons, spin-orbit
coupling provides the possibility for pure spin current. We introduce an
isospin to describe the level degree of freedom. This isospin feels an exchange
field similar to the exchange field in a quantum-dot spin valve. The exchange
field originates form the Coulomb interaction and its strength is sensitive
to the symmetry in the tunneling matrix elements. New features concerning
the pure spin pumping as well as the absolute pumped charge of the two-level
quantum dot with spin-orbit coupling arises from the Coulomb interaction.
[1] S. Rojek, J. König, and A. Shnirman, arXiv: 1209.4770v1 (2012)
[2] J. Splettstoesser, M. Governale, J. König, and R. Fazio, Phys. Rev. B
74, 085305 (2006).
[3] V. Brosco, M. Jerger, P. San-José, G. Zaránd, A. Shnirman, and G.
Schön, Phys. Rev. B 82, 041309(R) (2010).
Coauthors
Jürgen König and Alexander Shnirman
76

Posters Tuesday February 5
Poster 28:
Explicit staggered grid finite difference scheme for (2+1)D Dirac fermions
René Hammer
We study the dynamics of Dirac fermion wave packets on magnetically structured
surfaces of topological insulators and propose a gate-controlled Dirac
fermion interferometer based on a solitonic domain wall structure which functions
as a transistor. A preliminary summary of related work can be found
online (arXiv:1205.6941). Work supported by FWF Project P21289-N16
We discuss and compare several algorithms for a numerical solution of the
time-dependent Dirac equation in 2 spatial dimensions which allow the use of
a finite simulation region for open boundary situations. The newly proposed
explicit finite difference schemes use space and time staggering of the grid,
showing a computational complexity growing only linearly with the number
of space-time grid-points. One of them preserves the linear dispersion relation
of the Weyl equation for wave vectors aligned with the grid and yields only
one additional Dirac cone. The second scheme leads to a purely monotonic
free-particle dispersion avoiding an additional cone altogether. We discuss the
energy dispersion relation, the proof of stability, a definition of the norm on
the staggered grid, and the important issue of absorbing boundary conditions.
These schemes are useful for numerical studies of Dirac fermions on topological
insulators, where the surface state energy spectrum can be m! anipulat ed
by perturbations which break time-reversal symmetry introducing an energy
gap. Work supported by FWF Project P21289-N16
René Hammer, Christian Ertler, and Walter Pötz
Poster 29:
Microwave-controlled manipulation of Majorana bound states
Thomas Schmidt
Majorana bound states have been proposed as building blocks for qubits on
which certain operations can be performed in a topologically protected way
using braiding. However, the set of these protected operations is not sufficient
to realize universal quantum computing. We show that the electric field in
a microwave cavity can induce Rabi oscillations between adjacent Majorana
bound states. These oscillations can be used to implement an additional
single-qubit gate. Supplemented with one braiding operation, this gate allows
to perform arbitrary single-qubit operations.
77

Posters Tuesday February 5
Poster 30:
Topological edge states in a HgTe quantum well in proximity to an s-wave
superconductor
Luzie Weithofer
Topological insulators represent a new class of condensed matter systems
which are characterized by topologically protected edge states. Two-dimensional
topological insulators have been experimentally realized in HgTe
quantum wells [1]. In a HgTe quantum well in the topologically non-trivial
phase, two edge states of different spin propagate in opposite directions at
the same boundary.
Here, we consider the proximity-induced superconductivity in the bulk of
a HgTe quantum well in terms of a four-band model [2]. In addition, we
include various symmetry-breaking terms and discuss their consequences on
the topological properties of the system, focusing on the existence of edge
states.
[1] M. König et al., Science 318, 766 (2007) [2] B. Bernevig et al., Science
314, 1757 (2006)
Poster 31:
z→−z Symmetry of Spin-Orbit Coupling and Weak Localization in Graphene
Vladimir Falko
We show that the influence of spin-orbit (SO) coupling on the weak-localization
effect for electrons in graphene depends on the lack or presence of
z→−z symmetry in the system. While, for z→−z asymmetric SO coupling,
disordered graphene should display a weak antilocalization behavior at lowest
temperature, z→−z symmetric coupling leads to an effective saturation of
decoherence time which can be partially lifted by an in-plane magnetic field,
thus tending to restore the weak-localization effect.
78

Posters Tuesday February 5
Poster 32:
Intrinsic and substrate induced spin-orbit interaction in chirally stacked trilayer
graphene
Andor Kormanyos
We present a combined group-theoretical and tight-binding approach to
calculate the intrinsic spin-orbit coupling (SOC) in ABC stacked trilayer
graphene. As a special case of our calculations we also consider the intrinsic
SOC in bilayer graphene. The comparison between our tight-binding bilayer
results and the density functional computations of Konschuh et. al. allows
us to estimate the values of the trilayer SOC parameters as well. We also
discuss the situation when a substrate or adatoms induce strong SOC in
only one of the layers of bilayer or ABC trilayer graphene. Both for the
case of intrinsic and externally induced SOC we derive effective Hamiltonians
which describe the low-energy spin-orbit physics. We find that at the K point
of the Brillouin zone the effect of Bychkov-Rashba type SOC is suppressed
in bilayer and ABC trilayer graphene compared to monolayer graphene.
Poster 33:
Spin-orbit induced strong coupling of a single spin to a nanomechanical resonator
Andras Palyi
We theoretically investigate the spin-orbit-induced coupling of an electron
spin to a bending vibrational mode in suspended carbon nanotube quantum
dots. Our estimates indicate that, with current capabilities, a quantum dot
with an odd number of electrons can serve as a realization of the Jaynes-
Cummings model of quantum electrodynamics in the strong-coupling regime.
A bending mode of the suspended tube plays the role of the optical mode and
we identify two distinct two-level subspaces, at small and large magnetic field,
which can be used as qubits in this setup. The strong intrinsic spin-mechanical
coupling allows for detection, as well as manipulation of the spin qubit,
and may yield enhanced performance of nanotubes in sensing applications.
Reference:
A. Palyi, P. R. Struck, M. Rudner, K. Flensberg and G. Burkard, Phys.
Rev. Lett. 108, 206811 (2012)
79

Posters Tuesday February 5
Poster 34:
Spin-orbit effects in electronic transport in DNA-CNT hybrids
Sergio Ulloa
We report on theoretical studies of electronic transport in the archetypical
molecular hybrid formed by DNA wrapped around single-walled carbon
nanotubes (CNTs). Using a Green’s function formalism in a π-orbital tightbinding
representation, we investigate the role that spin-orbit interactions
play on the CNT in the case of the helicoidal electric field induced by the
polar nature of the adsorbed DNA molecule. We find that spin polarization
of the current can take place in the absence of magnetic fields, depending
strongly on the direction of the wrapping and length of the helicoidal field.
These findings open new routes for using CNTs in spintronic devices.
Poster 35:
Covalent functionalization of carbon nanotubes with tetramanganese complexes
Robert Frielinghaus
We present first results on the covalent chemical functionalization of carbon
nanotubes (CNTs) with polynuclear Mn 4 coordination complexes. Raman
spectra give direct and indirect evidence of a successful reaction. It can only
be achieved for tubes which contain defects with carboxylic groups. Changes
in the magnetization behavior of the Mn 4 complexes due to the bonding
to the CNTs are analyzed using data obtained in temperature-dependent
SQUID measurements.
These results are correlated with bright- and dark field high-resolution transmission
electron microscopy measurements that show the repartition of the
Mn 4 decoration on the CNTs. Its elemental analysis capabilities, energydispersive
x-ray spectroscopy and electron energy loss spectroscopy, proof the
existence of Mn on the CNTs. Investigating several oxidation strengths we
can show that already a mild oxidation that leaves the nanotubes intact in
terms of a finite electrical conductance is sufficient for functionalization. This
is important for the future application of this material in transport devices.
80

Posters Tuesday February 5
Poster 36:
Analysis of quantum transport features in complex carbon nanotube structures
Robert Frielinghaus
We have investigated two carbon nanotubes (CNTs) both in quantum transport
and in the transmission electron microscope by means of a novel sample
design. This enables us to determine the device structure unambiguously as
a two-fold single-walled CNT bundle and an individual triple-walled CNT,
respectively. The corresponding low-temperature transport experiments are,
to our knowledge, the first ones unambiguously conducted on these very
systems. The stability diagrams exhibit complex features as anti-crossings,
Fano-shaped coulomb peaks, and regular sawtooth patterns. The origin of
these features is only found with the detailed knowledge about the atomic
structure, which cannot be obtained with standard sample layouts. More precisely,
we measure capacitive and molecular interactions between the various
elements of the devices and the environment.
Poster 37:
Nanomechanical read-out of a single spin
Philipp Struck
The spin of a single electron in a suspended carbon nanotube can be read
out by using its coupling to the nano-mechanical motion of the nanotube. To
show this, we consider a single electron confined within a quantum dot formed
by the suspended carbon nanotube. The spin- orbit interaction induces a
coupling between the spin and one of the bending modes of the suspended
part of the nanotube. We calculate the response of the system to pulsed
external driving of the mechanical motion using a Jaynes-Cummings model.
To account for resonator damping, we solve a quantum master equation, with
parameters comparable to those used in recent experiments, and show how
information of the spin state of the system can be acquired by measuring
its mechanical motion. The latter can be detected by observing the current
through a nearby charge detector.[1]
[1] P. R. Struck, H. Wang, G. Burkard, arXiv:1212.1569
81

Posters Tuesday February 5
Poster 38:
Cotunneling renormalization in carbon nanotube quantum dots
Kirsanskas Gediminas
We determine the level shifts induced by cotunneling in a Coulomb blockaded
carbon nanotube quantum dot using leading-order quasi-degenerate
perturbation theory within a single nanotube “shell.” It is demonstrated
that otherwise degenerate and equally tunnel coupled K and K’ states are
mixed by cotunneling and therefore split up in energy except at the particle-hole
symmetric midpoints of the Coulomb diamonds. In the presence
of an external magnetic field, we show that cotunneling induces a gate dependent
g-factor renormalization, and we outline different scenarios which might
be observed experimentally, depending on the values of both intrinsic KK’-
mixing and spin-orbit coupling.
Poster 39:
Kondo effect in graphene with Rashba spin-orbit coupling
Diego Matrogiuseppe
We study the effect of Rashba spin-orbit coupling in graphene with an
adsorbed magnetic impurity. We model the system starting with a multiband
Anderson Hamiltonian, which is reduced to a single channel problem through
suitable fermionic redefinitions. Then we map it to a Kondo Hamiltonian
through a proper Schrieffer-Wolff transformation. The energy dependence
of the Kondo exchange coupling follows the functional form of the density
of states, giving rise to interesting phenomena as a function of the band filling.
Compared to plain graphene, the presence of Rashba spin-orbit induces a
finite density of states at the charge neutrality point. Therefore, a Kondo
phase is expected for any finite value of the Rashba parameter, even for
the particle-hole symmetric case. Finally, we compare these findings to recent
results of magnetic impurities on bilayer graphene without spin-orbit coupling.
Coauthors
S. Ulloa and N. Sandler
82

Posters Tuesday February 5
Poster 40:
Magnetic field effects on the finite-frequency noise and ac conductance of a
Kondo quantum dot out of equilibrium
Sarah Müller
We present analytic results for the finite-frequency current noise and the
nonequilibrium ac conductance for a Kondo quantum dot in presence of a
magnetic field. We determine the line shape close to resonances and show
that while all resonances in the ac conductance are broadened by the transverse
spin relaxation rate; the noise at finite field additionally involves the
longitudinal rate as well as sharp kinks resulting in singular derivatives. Our
results provide a consistent theoretical description of recent experimental
data [Phys. Rev. Lett. 108, 046802 (2012)] for the emission noise at zero
magnetic field, and we propose the extension to finite field for which we
present a detailed prediction.
Poster 41:
Electron entanglement in Cooper pair beam splitter with magnetic fields
Stephan Weiss
We develop a theory that suggests the efficient manipulation of entangled
electrons provided by a Cooper pair beam splitter. The splitting of coherent
electrons forming a spin singlet is present if the superconductor is tunnel
coupled to a double quantum dot [1]. In order to probe entanglement, we
allow for an inhomogeneous and, in general, non-collinear magnetic field in
both dots. If the DQD-SC system is embedded in a transport setup, non-local
current and noise properties are obtained within the real-time diagrammatic
method [2]. As a small parameter we use the hybridization between splitter
and normal leads. The tunnel coupling to the superconductor is taken into
account non-perturbatively. Furthermore, we provide a detailed investigation
of the violation of Bell’s inequality for various parameter regimes.
[1] J. Eldridge, M. Governale, and J. König, Phys. Rev. B 82 184507, (2010).
[2] M. Governale, M. Pala, and J. König, Phys. Rev. B 77 134513, (2008).
83

Posters Tuesday February 5
Poster 42:
Current correlations in the interacting Cooper-pair beam-splitter
Jerome Rech
We propose an approach allowing the computation of currents and their correlations
in interacting multi-terminal mesoscopic systems involving quantum
dots coupled to normal and/or superconducting leads [1]. The formalism
relies on the expression of branching currents and noise crossed correlations in
terms of one- and two-particle Green’s functions for the dots electrons, which
are then evaluated self-consistently within a conserving approximation [2].
We illustrate our method with the Cooper-pair beam-splitter setup recently
proposed [3], which we model as a double quantum dot with weak interactions,
connected to a superconducting lead and two normal ones. Our method
not only enables us to take into account a local repulsive interaction on the
dots, but also to study its competition with the direct tunneling between
dots. Our results suggest that even a weak Coulomb repulsion tends to favor
positive current cross correlations in the antisymmetric regime (where the
dots have opposite energies with respect to the superconducting chemical
potential).
Poster 43:
Controlling entanglement and spin-correlations in double quantum dots using
non-equilibrium currents
Carlos Busser
We study the non-equilibrium dynamics in a parallel double-quantum dot
structure induced by a large bias voltage. By applying both a magnetic flux
and a voltage, it is possible to generate spin-spin-correlations between the two
quantum dots, whose sign and absolute value can be controlled by changing
the bias voltage. Our study is based on the Anderson-impurity model and
we use time-dependent density matrix renormalization group simulations to
obtain currents and spin-correlations in the non-equilibrium regime.
84

List of participants
1. Yulieth Cristina Arango, Forschungszentrum Jülich, Germany
y.arango@fz-juelich.de
2. Christian Bartsch, TU Braunschweig, Braunschweig, Germany
c.bartsch@tu-braunschweig.de
3. Bernd Beschoten, RWTH Aachen University, Aachen, Germany
bernd.beschoten@physik.rwth-aachen.de
4. Stefan Blügel, Forschungszentrum Jülich, Germany
s.bluegel@fz-juelich.de
5. Aldo Brunetti, Heinrich Heine Univerität - Düsseldorf, Düsseldorf, Germany
brunetti@thphy.uni-duesseldorf.de
6. Carlos Busser, LMU Munich, Munich, Germany
C.Buesser@physik.uni-muenchen.de
7. Hernan Calvo, RWTH Aachen University, Aachen, Germany
hcalvo@physik.rwth-aachen.de
8. Theo Costi, Research Centre Jülich GmbH, Jülich, Germany
t.costi@fz-juelich.de
9. Silvano De Franceschi, CEA, Grenoble, France
silvano.defranceschi@cea.fr
10. Manuel dos Santos Dias, Forschungszentrum Jülich, Jülich, Germany
m.dos.santos.dias@fz-juelich.de
11. Reinhold Egger, Heinrich Heine Univerität- Düsseldorf, Düsseldorf, Germany
egger@thphy.uni-duesseldorf.de
12. Sigurdur I. Erlingsson, Reykjavik University, Reykjavik, Iceland
sie@ru.is
13. Vladimir Falko, Lancaster University, Lancaster, United Kingdom
v.falko@lancaster.ac.uk
14. Robert Frielinghaus, Forschungszentrum Jülich, Jülich, Germany
r.frielinghaus@fz-juelich.de
15. Robert Frielinghaus, Forschungszentrum Jülich, Jülich, Germany
r.frielinghaus@fz-juelich.de
16. Kirsanskas Gediminas, University of Copenhagen, Copenhagen, Denmark
gedikirs@nano.ku.dk
17. Thomas Gerster, Fz-Jülich, Jülich, Germany
t.gerster@fz-juelich.de
85

18. Domenico Giuliano, Universita‘ della Calabria - Italy, Rende, Italy
domenico.giuliano@fis.unical.it
19. Stephan Grap, RWTH Aachen University, Aachen, Germany
stephan.grap@rwth-aachen.de
20. Kasper Grove-Rasmussen, University of Copenhagen, Copenhagen, Denmark
k_grove@fys.ku.dk
21. Jan-Christian Gunia, Forschungszentrum Jülich, Germany
j-c.gunia@fz-juelich.de
22. René Hammer, University Graz, Graz, Austria
rene.hammer@uni-graz.at
23. Federica Haupt, RWTH Aachen University, Germany
federica.haupt@gmail.com
24. Sebastian Heedt, Forschungszentrum Jülich, Jülich, Germany
s.heedt@fz-juelich.de
25. Fabian Heidrich-Meisner, LMU Munich, Munich, Germany
heidrich-meisner@lmu.de
26. Stefan Heinze, University of Kiel, Kiel, Germany
heinze@physik.uni-kiel.de
27. Michael Hell, Research Center Jülich, Jülich, Germany
m.hell@fz-juelich.de
28. Carsten Honerkamp, RWTH Aachen, Germany,
honerkamp@physik.rwth-aachen.de
29. Christoph Hörig, RWTH, Aachen, German
hoerig@physik.rwth-aachen.de
30. Julen Ibanez, University of the Basque Country, Leioa (Bizkaia), Spain
julen.ibanez@ehu.es
31. Henrik Johannesson, University of Gothenburg, Gothenburg, Sweden
henrik.johannesson@physics.gu.se
32. Marvin Junk, RWTH Aachen, Aachen, Germany
Marvin.Junk@rwth-aachen.de
33. Pascal Kaienburg, RWTH, Aachen, Germany
pascal.kaienburg@rwth-aachen.de
34. Vladislav Kataev, IFW Dresden, Dresden, Germany
v.kataev@ifw-dresden.de
35. Michael Kinza, RWTH Aachen University, Aachen, Germany
kinza@physik.rwth-aachen.de
86

36. Jürgen König, University of Duisburg-Essen, Duisburg, Germany
koenig@thp.uni-due.de
37. Francois Konschelle, RWTH - Aachen, Aachen, Germany
konschelle@physik.rwth-aachen.de
38. Andor Kormanyos, University of Konstanz, Konstanz, Germany
andor.kormanyos@uni-konstanz.de
39. Martin Leijnse, Copenhagen University, Copenhagen, Denmark
leijnse@fys.ku.dk
40. Andrei Manolescu, Reykjavik University, Reykjavik, Iceland
manoles@ru.is
41. Charles Marcus, University of Copenhagen, Copenhagen, Denmark,
marcus@nbi.dk
42. Diego Matrogiuseppe, Ohio University, United States,
mastrogiuseppe@ifir-conicet.gov.ar
43. Volker Meden, RWTH Aachen, Aachen, Germany
meden@physik.rwth-aachen.de
44. Sebastian Mehl, Forschungszentrum Jülich, Jülich, Germany
s.mehl@fz-juelich.de
45. Lukas Merker, Forschungszentrum Jülich GmbH, Jülich, Germany
l.merker@fz-juelich.de
46. Maciej Misiorny, Forschungszentrum Jülich, Germany
m.misiorny@fz-juelich.de
47. Markus Morgenstern, RWTH, Aachen, Germany
mmorgens@physik.rwth-aachen.de
48. André Müller, RWTH Aachen, Germany
andre.mueller@physik.rwth-aachen.de
49. Sarah Müller, Universität Wien, Wien, Austria
sarah.mueller@univie.ac.at
50. Amin Naseri Jorshari, Heinrich Heine University, Dusseldorf, Germany
nasseri.amin@gmaul.com
51. Christoph Neumann, RWTH Aachen, Aachen, Germany
christoph.neumann@rwth-aachen.de
52. Hoa Nghiem, Forschungszentrum Jülich, Jülich, Germany
h.nghiem@fz-juelich.de
53. Christoph Ohm, RWTH Aachen, Aachen, Germany
ohm@physik.rwth-aachen.de
54. Sander Otte, TU Delft, Delft, The Netherlands
a.f.otte@tudelft.nl
87

55. Jens Paaske, Copenhagen University, Copenhagen, Denmark
paaske@nbi.ku.dk
56. Andras Palyi, Eotvos University Budapest, Budapest, Hungary
andraspalyi@caesar.elte.hu
57. Mikhail Pletyukhov, RWTH, Aachen, Germany
pletmikh@physik.rwth-aachen.de
58. Vlad Pribiag, TU Delft, Delft, The Netherlands
v.s.pribiag@tudelft.nl
59. Benedikt Probst, TU Braunschweig, Braunschweig, Germany
b.probst@tu-braunschweig.de
60. Jerome Rech, Aix Marseille Université, Marseille, France
jerome.rech@cpt.univ-mrs.fr
61. Maria-Theresa Rieder, Freie Universität Berlin, Berlin, Germany
riederm@physik.fu-berlin.de
62. Stephan Rojek, Universität Duisburg-Essen, Duisburg, Germany
strojek@thp.uni-due.de
63. Achim Rosch, University of Cologne, Cologne, Germany
rosch@thp.uni-koeln.de
64. Julia Samm, University of Basel, Basel, Switzerland
julia.samm@unibas.ch
65. Nancy Sandler, Freie Universitat/Ohio University, Berlin, Germany
sandler@ohio.edu
66. Roman Saptsov, Forschungszentrum Jülich, Jülich, Germany
r.saptsov@fz-juelich.de
67. Thomas Schäpers, Forschungszentrum Jülich and RWTH Aachen, Jülich,
Germany
th.schaepers@fz-juelich.de
68. Thomas Schmidt, Universität Basel, Basel, Switzerland
thomas.schmidt@unibas.ch
69. Michael Schnee, Forschungszentrum Jülich, Jülich, Germany
m.schnee@fz-juelich.de
70. Herbert Schoeller, RWTH Aachen University, Aachen, Germany
schoeller@physik.rwth-aachen.de
71. Christian Schönenberger, University of Basel, Basel, Switzerland
Christian.Schoenenberger@unibas.ch
72. Llorens Serra, University of Balearic Islands, Palma de Mallorca, Spain
llorens.serra@uib.es
88

73. Janine Splettstoesser, RWTH Aachen, Aachen, Germany
splett@physik.rwth-aachen.de
74. Christoph Stampfer, RWTH Aachen, Aachen, Germany
christoph@stampfer.com
75. Philipp Stegmann, Universität Duisburg-Essen, Duisburg, Germany
philipp.stegmann@uni-due.de
76. Robin Steinigeweg, TU Braunschweig, Braunschweig, Germany
robin@robin-st.de
77. Anders Ström, TU Braunschweig, Braunschweig, Germany
anders.p.strom@gmail.com
78. Philipp Struck, University of Konstanz, Konstanz, Germany
philipp.struck@uni-konstanz.de
79. Arturo Tagliacozzo, Universita’ di Napoli "Federico II", Napoli , Italy
arturo@na.infn.it
80. Seigo Tarucha, University of Tokyo, Tokyo, Japan
tarucha@ap.t.u-tokyo.ac.jp
81. Jonckheere Thibaut, CNRS , Marseille, France
thibaut.jonckheere@cpt.univ-mrs.fr
82. Carsten Timm, Technische Universität Dresden, Dresden, Germany
carsten.timm@tu-dresden.de
83. Mircea Trif, UCLA, Los Angeles, United States
mtrif@physics.ucla.edu
84. Sergio Ulloa, Ohio University, Athens, Ohio, USA
ulloa@ohio.edu
85. Herre van der Zant, Delft University of Technology, Delft, The Netherlands
h.s.j.vanderzant@tudelft.nl
86. Ilse van Weperen, Delft University of Technology, Delft, The Netherlands
I.vanWeperen@tudelft.nl
87. Christian Volk, RWTH Aachen, Aachen, Germany
c.volk@fz-juelich.de
88. Stephan Weiss, Universität Duisburg-Essen, Duisburg, Germany
weiss@thp.uni-due.de
89. Luzie Weithofer, TU Braunschweig, Braunschweig, Germany
luzie.weithofer@tu-bs.de
90. Ireneusz Weymann, Adam Mickiewicz University, Poznan, Poland
weymann@amu.edu.pl
89