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MA: Fachverband Magnetismus

MA 9: Spin Excitations/Spin Torque

MA 9.3: Vortrag

Montag, 16. März 2015, 16:00–16:15, H 0112

Direct and inverse spin-orbit torques from first principles — •Frank Freimuth, Stefan Blugel, and Yuriy Mokrousov — Peter Grünberg Institut & Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany

Ferromagnetic (FM) layers asymmetrically sandwiched between nonmagnetic (NM) layers can be switched by spin-orbit torques (SOTs) [1,2]. Conversely, an electric current can be induced by magnetization dynamics due to the inverse SOT (ISOT) [3]. We discuss exact relationships between SOTs and ISOTs. Based on DFT calculations [4] we study (I)SOTs in NM/FM thin films for various choices of NM (Pt, W, Ta, Ir, Au) and FM (Co, Fe, Mn). Resolving torques and spin-fluxes on the atomic scale allows us to differentiate between local and non-local contributions. An important contribution to the ISOT is the conversion of pumped spin current into charge current via the inverse spin Hall effect (ISHE). We investigate the spatial decay of the spin current pumped into NM via the ferromagnetic resonance (FMR) of the FM layer, its conversion into a charge current and its contribution to the Gilbert damping. We show that this ISHE-driven charge current is accompanied by a phase-shifted contribution originating in the interfacial spin-orbit coupling. Finally, we investigate (I)SOTs at finite frequencies and find that they can be very well approximated by the zero-frequency (I)SOTs in the GHz regime.

[1] F. Freimuth et al., PRB 90, 174423 (2014)

[2] F. Freimuth et al., J. Phys.: Condens. Matter 26, 104202 (2014)

[3] F. Freimuth et al., arXiv:1406.3866 [4] www.flapw.de