Spin Wave Interactions by a Continuous Medium Model

Abstract

A new expression for the energy due to the fluctuation of the magnetization is found for an isotropic continuous ferromagnetic medium. By using the Holstein-Primakoff transformation, it is shown that the terms in this expression except the first term, which was discussed by Herring and Kittel, correspond to spin wave-spin wave interactions, which have the same form as that discussed by Marshall in the energy of spin waves. An expression for the exchange field including the term corresponding to a term of the fourth power of spin wave momentums in the energy of spin waves is found.