Quantum magnetization fluctuations via spin shot noise

Abstract

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.

4.5 pages, 2 figures

References in corpus (3)

• Spin Transfer Torques
• Spin transfer due to quantum fluctuations of magnetization
• Magnetization Dynamics driven by Non-equilibrium Spin-Orbit Coupled Electron Gas

Cited by in corpus (6)

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• Quantum Scattering Theory of Spin Transfer Torque, Spin Pumping and Fluctuations
• Thermal squeezing and nonlinear spectral shift of magnons in antiferromagnetic insulators
• Quantum noise in the spin transfer torque effect