Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 42: Joint Session "Novel Spincaloritronic Devices: Control of Heat, Charge and Momentum Flow" (jointly with TT), Organization: Markus Münzenberg (Univ. Göttingen), Mathias Weiler (WMI Garching)

MA 42.5: Topical Talk

Donnerstag, 29. März 2012, 17:00–17:30, EB 301

Spin waves and spin currents in hybrid magnetic nanostructures — •Sergej O. Demokritov — Institute for Applied Physics, University of Muenster, Muenster, Germany

Unlike the charge current, the spin current, i.e., the flow of angular momentum without the simultaneous transfer of electrical charge, is not a conservative quantity within the conduction carrier system. This is due to the spin orbit interaction that couples the spin of the carriers to angular momentum in the lattice. This coupling usually acts as the source of damping for spin currents; the excess angular momentum in the magnetic subsystem flows into the lattice.

In this talk I will discuss our recent experiments [1] on the YIG/Pt hybrid system, where we show that this flow can be reversed by the three-magnon splitting process and experimentally achieve amplification of spin current due to interaction of spin waves with the lattice.

Finally I will address the interaction of spin current with thermal magnetic fluctuations in a Permalloy microdisk located on top of a Pt microstrip [2]. The spin current in the microdisk is generated by an electric current flowing through the microstrip. We show that the fluctuations in the microdisk can be efficiently suppressed or enhanced by spin currents with different polarizations. The observed phenomenon can be used for controllable reduction of thermal noise in spintronic nanodevices.

[1] H. Kurebayashi et al., Nature Materials, 10 (2011) 660.

[2] V. E. Demidov et al., Phys. Rev. Lett. 107 (2011) 107204