Phase-Flow Interpretation of Magnetization Relaxation in Nanomagnets

This paper is devoted to the study of the probability of relaxation of a bistable nanomagnet from high energy to one of its two energy minima. The evolution in phase space of a Gibbs ensemble of replicas of the nanomagnet is analyzed in the limit of small Gilbert damping and in the absence of thermal noise. It is shown that when an external magnetic field is applied along the intermediate anisotropy axis, the relaxation probability exhibits a saw-tooth dependence on the field amplitude, periodically reaching the extreme values 0 or 1, in correspondence to which relaxation is fully insensitive to randomness in initial conditions.