DETERMINATION OF THE DOMAIN WALL ENERGY AND THE EXCHANGE CONSTANT FROM HYSTERESIS IN FERRIMAGNETIC POLYCRYSTALS

Abstract

A fundamental law previously found in YIG, which relates the hysteresis losses to the magnetization state is generalized to Ni ferrite and to mixed NiZn and NiCd ferrites. The interpretation which is given is based on the domain wall size theory previously proposed by Globus : the energy lost by the continuous pinning and depinning of the domain wall as it moves and the energy lost by the formation and the destruction of a part of the domain wall surface may be the origins of the losses which find their expression in the hysteresis loop. That results in an experimental method to determine, from simple measurements of loop areas on polycrystalline samples, the domain wall energy γ and the exchange constant A.