Disorder effects on the metastability of classical Heisenberg ferromagnets

Abstract

In the present paper, we investigate the effects of disorder on the reversal time (τ ) of classical anisotropic Heisenberg ferromagnets in three dimensions by means of Monte Carlo simulations. Starting from the pure system, our analysis suggests that τ increases with increasing anisotropy strength. On the other hand, for the case of randomly distributed anisotropy, generated from various statistical distributions, a set of results is obtained: (i) For both bimodal and uniform distributions, the variation of τ with the strength of anisotropy strongly depends on temperature. (ii) At lower temperatures, the decrement in τ with increasing width of the distribution is more prominent. (iii) For the case of normally distributed anisotropy, the variation of τ with the width of the distribution is nonmonotonic, featuring a minimum value that decays exponentially with the temperature. Finally, we elaborate on the joint effect of longitudinal (h z ) and transverse (h x ) fields on τ , which appear to obey a scaling behavior of the form τ h n z ∼ f (h x ).