Atomic Moments, Anisotropy and Exchange Coupling in Ultrathin Films: Magnetic Order and Structure

Abstract

In recent years a series of new phenomena related to magnetic properties of ul-trathin films and multilayers have been theoretically predicted or discovered empirically, e. g. atomic magnetic moments which are enhanced compared to bulk matericJ, magnetic surface and interface anisotropics which often have an easy axis of magnetization perpendicular to the film plane, exchange coupling between ferromagnetic layers across non-magnetic spacer layers which is observed frequently to oscillate between ferro- and antiferromagnetic as a function of spacer layer thickness, spin dependent scattering of conduction electrons in multilayers which leads to a giant magnetoresistance if neighbouring ferromagnetic layers have antiparallel magnetization. However, experimental data often deviate considerably from one laboratory to another. This fact has led to certain controversies but, indeed, it most certainly indicates a strong dependence of the magnetic behaviour on film structure and morphology. These in turn are strongly influenced by the growth conditions for the films which are not perfectly controlled in many experiments.