HREM contributions to microstructural investigations of magnetic thin films and ultrathin multilayers

Abstract

Magnetic thin films and ultrathin multilayers(ML) have been developed which are of great fundamental and technological interest Since their physical properties depend strongly upon growth conditions, it requires microstructural investigations to establish and understand their interrelationship. The required information about thin films includes, for example, layer-layer and layer-substrate interfaces, crystallinity, crystal type, columnar growth, crystal orientations and so on, all of which could influence or even totally change the macrobehavior. Unlike other commonly used structural determination techniques which average over comparatively large volumes, HREM provides real-space information on the atomic scale. It has been demonstrated to be an ideal method for investigating thin film microstructure, especially for ultrathin ML with bilayer thicknesses on the nanometer scale. A limitation of electron microscopy is that the information is obtained from twodimensional projections of the sample. However, thin films and ML can be prepared in both cross-section and plan-view. It is thus usually possible to obtain quasi-3D information and answer important structural questions about crystalline, polycrystalline and amorphous-like thin films.