Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 7: Spin-Dynamics/ Spin-Torque II
MA 7.5: Vortrag
Montag, 23. März 2009, 16:15–16:30, HSZ 04
Spin-torque shot noise — •Jacek Swiebodzinski1, Alexander L. Chudnovskiy1, and Alex Kamenev2 — 1I. Institut für Theoretische Physik, Universität Hamburg, Jungiusstraße 9, D-20355 Hamburg, Germany — 2Department of Physics, University of Minnesota, Minneapolis, Minnesota 55455, USA
The role of spin shot noise in magnetization dynamics, though being the dominant contribution to magnetization noise at low temperatures, remains largely unexplored yet. We propose a stochastic version of the Landau-Lifshitz-Gilbert equation taking into account both, thermal and nonequilibrium sources of noise and apply this equation to a system consisting of a free ferromagnetic layer in contact with a fixed ferromagnet. We derive the noise correlator in the magnetic tunnel junction setup using the Keldysh technique. We solve the corresponding Fokker-Planck equations and show that the spin shot noise yields to the experimentally observed nonmonotonic dependence of the precession spectrum linewidth on the current.