A model for the field dependence of magnetization discontinuities in high-anisotropy materials

A simple model involving two types of nuclei, neither with any unusual or unsymmetrical properties, can describe a large variety of phenomena related to the field dependence of coercive force in powders and nucleating fields in single particles of high-anisotropy materials, including orthoferrites and hexagonal oxides as well as cobalt-rare-earths. One type of nucleus is a domain wall trap that is activated by capturing a fragment of moving wall. The other type is any local disturbance that provides a reversal site by its interaction with the local magnetization. Together they permit reasonable quantitative predictions of a number of types of behavior that have been observed.