Berlin 2018 – scientific programme

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MA: Fachverband Magnetismus

MA 27: Spin currents and spin torques

MA 27.9: Talk

Wednesday, March 14, 2018, 11:45–12:00, EB 407

Persistent precessions in spin-torque systems far from equilibrium — •Tim Ludwig¹, Igor Burmistrov^1,2,3, Yuval Gefen⁴, and Alexander Shnirman¹ — ¹Institut für Theorie der Kondensierten Materie, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany — ²L. D. Landau Institute for Theoretical Physics RAS, 119334 Moscow, Russia — ³Institut für Nanotechnologie, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany — ⁴Department of Condensed Matter Physics, Weizmann Institute of Science, 76100 Rehovot, Israel

We consider persistent precessions of an itinerant single domain nano-magnet driven by a thermally induced spin-transfer torque current. In [1] it was found that, far from equilibrium, stationary adjustments of the electronic distribution functions can render electrically driven persistent precessions unstable. In contrast, as we now show, stable persistent precessions can be maintained by thermal driving even far from equilibrium. Interestingly, to obtain consistent results for the stability, we have to include dynamic adjustments of the distribution function to the trajectory of the magnetization. On the technical level, we follow the approach of [1], i.e., we derive an effective action of the Ambegaokar-Eckern-Schön type for the magnetization. For the determination of the stability, we have to extend the calculations of [1] and include higher orders terms.

[1] T. Ludwig, I.S. Burmistrov, Y. Gefen, A. Shnirman Phys. Rev. B 95, 075425 (2017)