Eine mikromagnetische Ableitung der „Grundregeln“ für magnetische Bereichsstrukturen in massiven Kristallen

Abstract

A result of experimental investigations of magnetic domain pattern was, simply said, that the domains are always aranged in such a way, that magnetic stray-fields are avoided everywhere, and only easy directions are occupied by the magnetization. This is true for domains in the bulk of the specimen as well as for the surface. This result — which may be described by two basic rules for magnetic domains — will now be derived theoretically. The idea is to examine the stability of an arbitrary volume with respect to a certain variation of the magnetization; the variation leads two what may be called an incomplete Bloch-wall. It results from the calculation, that in a ferromagnetic crystal every volume element, which is homogenously magnetized and large as compared to the thickness of a Bloch-wall, can be looked at as more or less independently variable. The basic rules follow from this argument. The range of validity, the significance and possible applications of our rules are discussed.