Model of magnetization viscosity in Stoner-Wohlfarth particles

It is well known that hysteresis has its physical origin in the multiplicity of metastable states. Random perturbations of thermal or other nature may cause a gradual motion of the hysteretic system from one metasable state to others resulting in slow changes of the output variables (such as magnetization). This phenomenon is referred to as "viscosity" or "creep". Recently, Preisach's hysteresis model with stochastic input has been proposed as a model of viscosity in hysteretic systems. Later, this model was generalized to include materials which can be described by hysteresis loops of the Stoner-Wohlfarth particles (or their assembly). In this paper, a model of magnetization viscosity in the Stoner-Wohlfarth particles is obtained for the most general case of vector valued magnetic field and magnetization.