Theory of Reversible Magnetization in Ferromagnetics

Abstract

In the statistical domain theory of Heisenberg and others it is assumed that the domains have constant volumes, but that their magnetic moments change from one direction to another as the field or stress is changed. This model is highly artificial, for the actual process is believed to be a growth of some domains at the expense of others by displacement of the boundary between them. In this article the equations of the statistical theory are derived without use of the simplified model, by an adaptation of Kondorsky's analysis of the boundary displacement process. The assumptions necessary for this derivation are discussed critically, and the effect of modifying them is investigated in several special cases.