Regensburg 2019 – scientific programme

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MA: Fachverband Magnetismus

MA 26: Spin dynamics and transport

MA 26.6: Talk

Wednesday, April 3, 2019, 10:45–11:00, H37

Quantum fluctuations of magnetization via spin shot noise — •Alireza Qaiumzadeh and Arne Brataas — Center for Quantum Spintronics, NTNU, Norway

Recent experiment in current-driven spin valves demonstrate magnetization fluctuations that deviate from semiclassical predictions [1]. We posit that the origin of this deviation is the spin shot noise. On this basis, our theory predicts that the 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 [2]. Our theory shows the important contribution of so far overlooked spin shot noise on spin transfer torque phenomena.

[1] A. Zholud, R. Freeman, R. Cao, A. Srivastava, S. Urazhdin, Phys. Rev. Lett. 119, 257201 (2017). [2] A. Qaiumzadeh and A. Brataas, arXiv:1808.02907 (2018).