Abstracts Book - IMRC 2018

• SF1-O008 Invited Talk
ROLE OF DIPOLAR INTERACTIONS IN SPIN TRANSFER TORQUE
NANO-OSCILLATORS
Dora Altbir 1,2 , Daniela Mancilla Almonacid 1,2 , Rodrigo E. Arias 1,3 , Simon Oyarzun 1,2 , Roberto
Escobar 1 , Sebastian Allende 2,4
1 Center for the Development of Nanoscience and Nanotechnology, Magnetic nanostructure,
Chile. 2 Universidad de Santiago de Chile, Physics, Chile. 3 Universidad de Chile, Physics, Chile.
4 Center for the Development of Nanoscience and Nanotechnology, , Chile.
During the last two decades there has been a strong interest on spin transfer
torque nano-oscillators (STNOs) which are motivated mainly by their potential
applications 1,2 . These structures are composed by two ferromagnetic layers,
called the “fixed” and the “free” layers, separated by a nonmagnetic spacer.
When injecting a critical dc current, normal modes of the free layer reach an
auto-oscillation regime. Interest in understanding the magnetization dynamics
in these structures has lately arised since they may emulate neuron and synapse
behaviour 3 . To analyze such behavior, we focus this work on the spin wave
modes of one isolated and two interacting STNOs. By using a standard
Hamiltonian formalism, we obtain analytical expressions for the
eigenfrequencies, and observe that dipolar interactions are responsible of
important changes on the critical current, allowing a reduction in the energy
consumption of these systems. For two STNOs, two normal modes are obtained,
that exhibit different behavior as a function of the relative position of both
pillards.
1
E. Chen, et al, IEEE Trans. Magn. 46, 1873 (2010).
2
T. Kawahara, K Ito, R. Takemura, and H. Ohno, Microelectronics Reliability 52,
613 (2012).
3
N. Locatelli, V. Cros, J. Grollier, Nature Materials 13, 11 (2014).
Acknowledgment:
We acknowledge financial support in Chile FONDECYT 1161018, 1160198 and
1170781, Financiamiento Basal para Centros Científicos y Tecnológicos de
Excelencia FB 0807, and AFOSR FA9550-16-1-0384.
Keywords: dipolar interactions, in spin transfer torque, nano-oscillators
Presenting authors email: dora.altbir@usach.cl