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MA: Fachverband Magnetismus

MA 53: Magnonics II

MA 53.1: Vortrag

Donnerstag, 19. März 2020, 15:00–15:15, HSZ 401

Quantum spin transfer due to spin shot noise — •Alireza Qaiumzadeh and Arne Brataas — Center for Quantum Spintronics, Norwegian University of Science and Technology

Recent measurements in current-driven spin valves demonstrate magnetization fluctuations that deviate from semiclassical predictions. We posit that the origin of this deviation is spin shot noise. On this basis, our theory predicts that magnetization fluctuations asymmetrically increase in biased junctions irrespective of the current direction. At low temperatures, the fluctuations are proportional to the bias, but at different rates for opposite current directions. Quantum effects control fluctuations even at higher temperatures. Our results are in semiquantitative agreement with recent experiments and are in contradiction to semiclassical theories of spin-transfer torque [1].

[1] Phys. Rev. B 98, 220408(R) (2018)