A kinetic theory of micromagnetic time evolution

A semi-analytic description of recording media grainsʼ magnetization flipping in a magnetic field provides hysteresis loops, efficiently, with all parameters found by following orbits, and in close agreement with existing results. Integrating the Landau-Lifshitz-Gilbert (LLG) equations numerically gives the average energy diffusion coefficient Dϵ, energy loss rate aϵ and the barrier height which must be overcome. These allow solution of the kinetic equation for the probability density f and the escape rate γ of a grain trapped in an energy well, as well as other, similar, very stiff systems. γ is used in Monte Carlo simulation of hysteresis. The essential physics governing the grainsʼ behavior is outlined.