Pinning and minor loops in an inclusive model of ferromagnetic hysteresis

Pinning and minor loops are treated in an inclusive macroscopic model of ferromagnetic hysteresis. The model is developed from a Stoner-Wohlfarth approach and includes pinning effects, like the Jiles-Atherton model, Complicated sets of field turning points, typical of the Preisach model, are included. The extensions made here to the Stoner-Wohlfarth model, particularly the pinning effects, constitute a hypothetical study of ferromagnetism within the confines of an idealized numerical model, and do not necessarily correspond to the behavior of known magnetic materials. Computational approaches to two-dimensional calculations are outlined and results are given. The minor loops are seen to exhibit incongruence and eventual closure.

I. Introduction

The Stoner-Wohlfarth (S-W) model [1] of ferromagnetic hysteresis describes magnetization processes in terms of domain magnetization rotation in an anisotropic crystal. The ferromagnetic materials whose behavior is particularly well modeled are the hard magnetic materials, such as ferrite permanent magnets. An isotropic polycrystalline ferromagnet can consist of an isotropic collection of crystals, which individually exhibit magnetocrystalline anisotropy.