Noise and dissipation in magnetoelectronic nanostructures

We study the coupled current and magnetization noise in magnetic nanostructures by magnetoelectronic circuit theory. Spin current fluctuations, which depend on the magnetic configuration, are found to be an important source of magnetization noise and damping in thinly layered systems. The enhanced magnetization fluctuations in spin valves can be directly measured by their effect on the resistance noise.