MAGNETIC COUPLING OF CO LAYERS THROUGH A CU SPACER LAYER

In this paper we present results of investigations of the magnetic coupling of Co layers through a Cu spacer layer. These were obtained by examining Co/Cu/Co sandwich layers by Lorentz microscopy in the Fresnel and Foucault imaging mode. Ferromagnetic (F) and antiferromagnetic (AF) coupling of the magnetic Co layers can be found for different Cu spacer layer thicknesses. For the F coupled sandwich layer twin walls have been observed and the Co layers are only F coupled throughout the specimen. For the mainly AF coupled sandwich layer we observed a partial F and AF coupling of the Co layers which can be explained by thickness fluctuations of the Cu interlayer. Although we have to expect thickness fluctuations of the Co spacer layer in the F and the mainly AF coupled system, we only observe partial F and AF coupling for the mainly AF coupled system and not for the F coupled system. Therefore AF coupling is much more sensitive to thickness fluctuations than F coupling.