Numerical study of spin relaxation by thermal fluctuation: Effect of shape anisotropy

Abstract

Effects of the shape anisotropy on the thermally activated spin relaxation have been investigated using the stochastic Landau-Lifshitz-Gilbert equation. The relaxation times of a noninteracting particle and a thin film were compared with each other. In a noninteracting particle, the relaxation time largely increased with the shape anisotropy when the damping constant was smaller than a certain critical value. In this study, the critical damping constant was 0.02. However, the effect of the shape anisotropy on the energy barrier was negligible in a thin film. All of these results can be explained from the effect of magnetostatic interaction that is enhanced by precession motion at low damping constant.