Roughness Measurements on Thin Magnetic Layers using Energy-Filtering TEM

Abstract

In the deposition process of thin layers the surface roughness of the substrate as well as the roughness of layers and/or interfaces may have a strong influence on their physical properties. For example, the interfacial roughness has turned out to have a big influence on the magnetic behavior in exchange-coupled antiferromagnetic and ferromagnetic thin films. Since roughness can be of different kinds, one has to differentiate between physical, chemical and in this case, magnetic roughness. The former two can be differentiated in terms of their spatial frequency or ‘wavelength': for chemical roughness the local chemistry (ie. the positions of individual atoms) is crucial, meaning, that it takes place at very short wavelengths. On the other hand, physical roughness is determined by wavelengths much longer than atomic distances.The surface roughness of a material (physical roughness) is often measured using an atomic force microscope. If interfacial roughness is of interest, cross-sectional samples have to prepared in order to have access to the desired information.