On the 2-dimensional spinwave theory for ferro- and antiferromagnetic thin films

Abstract

The 2-dimensional approach to the spinwave theory for magnetic thin films is applied to the study of ferro- or antiferromagnetic films of varying thickness. The ferrimagnetic problem is also briefly considered. The variation through the layers of the dipolar anisotropy fields has been calculated. The effects of the dipolar interactions are thus taken into account by including into the interaction hamiltonian a term containing an anisotropy field that can be different for each of the layers constituting the film. In this way the contribution of the dipolar interactions to the surface pinning for ferro- and antiferromagnetic films could be estimated. The spontaneous magnetization or sublattice magnetization has been studied as a function of film thickness and anisotropy. The variation throughout the layer of the magnetization is explicitly considered, in order to separate the effects of surface pinning due to the dipolar field variation from that coming from the decrease in the number of nearest neighbours at the surface (natural defect). Furthermore the convergency with increasing film thickness of the film behaviour from the monolayer limit to the three-dimensional bulk behaviour is considered.