Dresden 2020 – scientific programme
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MA: Fachverband Magnetismus
MA 14: General Spintronics
MA 14.5: Talk
Monday, March 16, 2020, 16:00–16:15, HSZ 401
Noise-driven magnetic spin dynamics for an insulating Heisenberg magnet coupled to a metallic lead — •Benjamin F. McKeever1, Karin Everschor-Sitte1, and Kei Yamamoto2 — 1Institute of Physics, Johannes Gutenberg-Universität, 55128 Mainz, Germany — 2Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
Near interfaces between a magnet and a non-magnetic metal, Gilbert damping in magnetic spin dynamics is enhanced due to spin-dependent scattering of conduction electrons. The enhancement corresponds to a transfer of spin angular momentum into the normal metal from the magnet (spin pumping), with strength determined by the spin mixing conductance. Similarly, the reciprocal effect, where spin-angular momentum is transferred into the ferromagnet from the normal metal, is pertinent when applying an electric current (Slonczewski spin-transfer torque). To go beyond the paradigm of magneto-electric circuit theory which defines the mixing conductance, and to tie together the different relevant effects, we investigate the role of interface-induced noise fluctuations in the spin dynamics; this is done by modelling the coupling between the normal metal conduction electron spin density and magnetic insulator spins with sd exchange interaction for any kind of magnetic spin system. Ferromagnetic and antiferromagnetic spin chains are presented as example applications of the resulting stochastic LLG equation, which is accurate up to second order in the sd exchange. The formalism presents a way to address interface-driven nonequilibrium noise effects in heterostructures with thin magnetic layers.