Influence of impurities on dynamic hysteresis of magnetization reversal

Abstract

The effects of impurities on driving-rate-dependent energy loss in ferromagnets are investigated by analyzing several well-defined models for magnetization reversal. The random-field Ising models are analyzed using a mean-field approximation and Monte Carlo simulation. The hysteresis loop area A is found to obey a universal scaling relation with respect to the linear driving rates h of the applied field, $A\ensuremath{-}{A}_{0}\ensuremath{\propto}{h}^{\ensuremath{\beta}}.$ The scaling exponent \ensuremath{\beta} is found independent of the disorder strength D. In a random-field spherical model, the energy loss increases as a power law with the driving rate $A\ensuremath{\propto}{h}^{\ensuremath{\beta}(D)}.$ The scaling exponent $\ensuremath{\beta}(D)$ increases with increasing D. These results indicate that the scaling and universality for the field-driven first-order phase transition can be understood in the framework of dynamic hysteresis.