Magnetization noise in magnetoelectronic nanostructures

Authors: Arne Brataas, Jorn Foros, Yaroslav Tserkovnyak and Gerrit E. W. 
Bauer

Abstract: By scattering theory we show that spin current noise in normal 
electric conductors in contact with nanoscale ferromagnets increases the 
magnetization noise by means of a fluctuating spin-transfer torque. 
Johnson-Nyquist noise in the spin current is related to the increased 
Gilbert damping due to spin pumping, in accordance with the 
fluctuation-dissipation theorem. Spin current shot noise in the presence 
of an applied bias is the dominant contribution to the magnetization noise 
at low temperatures.