On a simple derivation of the very low damping escape rate for classical spins by modifying the method of Kramers
arXiv:1908.06747 · doi:10.1016/j.physa.2019.121195
Abstract
The original perturbative Kramers' method (starting from the phase space coordinates) (Kramers, 1940) of determining the energy-controlled-diffusion equation for Newtonian particles with separable and additive Hamiltonians is generalized to yield the energy-controlled diffusion equation and thus the very low damping (VLD) escape rate including spin-transfer torque for classical giant magnetic spins with two degrees of freedom. These have dynamics governed by the magnetic Langevin and Fokker-Planck equations and thus are generally based on non-separable and non-additive Hamiltonians. The derivation of the VLD escape rate directly from the (magnetic) Fokker-Planck equation for the surface distribution of magnetization orientations in the configuration space of the polar and azimuthal angles is much simpler than those previously used.
arXiv comment16 pages, 1 figure. Published in: Physica A: Statistical Mechanics and its Applications. Journal reference: Physica A, volume 527, 121195. Date of Publication: 1 August 2019. Publisher: Elsevier
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