Estimation of the Effects of Microscopic Misalignments on the Magnetization Process in Thin Films by Energetic Modeling

In the framework of an energetic model, which is based on a stochastic description of the macroscopic magnetization process, we want to explain how misalignments of microscopic magnetic dipoles influence the magnetization curve. In contrast to previous work, the orientation of the elementary magnetic dipoles is modeled via statistical distribution functions that are characterized by a mean orientation and a corresponding variance that accounts for misalignments. This nonuniform orientation can result from structural defects in the crystal lattice, for example. The model is applied to thin-film permalloy samples that are used in anisotropic magnetoresistive sensor elements. Here, the variance of the angular distribution function is a measure for inhomogeneities in the film. Furthermore, it can be shown how technological parameters of the sputter process influence the alignment of the magnetic moments and, thus, determine the magnetoresistive characteristics of the sensor element.