Field orientations and sweep rate effects on magnetic switching of Stoner–Wohlfarth particles

Abstract

Field angles and sweep rate dependence of coercivity of the Stoner–Wohlfarth (S-W) particles are studied based on the decay-rate model. An analytic expression of the hysteresis loops based on the model is obtained as a function of applied field for various frequencies at various field angles with respect to the easy axis. Variation of the coercivities versus the sweep rate (measurement frequency), field angles, anisotropy constant, activation volume, and the combination thereof, and the distribution of easy axis, etc., have been obtained. Comparison with the thermal-equilibrium and S-W hysteresis loops are made. Coercivities of such a system generally increase with increasing sweep rate, anisotropy constant and activation volume, etc., hence decreases with increasing sweeping period. As a function of the field angles, the coercivity curve turns flat with increasing field angles and sweeping period.