Magnetic properties of small chromium and gadolinium clusters, deposited on magnetic substrates

Small, on magnetic substrates deposited clusters show a complex magnetic behavior. The intrinsic parameters of the measured magnetic properties are the cluster size, the cluster-substrate-interaction as well as the degree of localization of the electrons, being responsible for the observed magnetic properties. In the present thesis, Chromium clusters deposited on magnetic Fe/Cu(100) and Ni/Cu(100) substrates as well as Gadolinium and Gadolinium oxide clusters deposited on magnetic Fe/Cu(100) substrates have been investigated. The magnetic properties have been determined using x-ray magnetic circular dichroism (XMCD). Deposited Chromium clusters, which are an example for delocalized electron systems, show a strong dependence of the observed magnetic properties of the cluster size as well as of the cluster-substrate-interaction. The comparison of the experimental results with the results of calculations show that the magnetic properties can be described by a non-collinear coupling of the local magnetic moments. The origin of the non-collinear magnetic coupling is related to the interplay between antiferromagnetic coupling and magnetic frustration. Small Gadolinium and Gadolinium oxide clusters show a different magnetic behavior. Due to the strong localization of the electrons carrying the magnetism, the magnetic properties of these clusters are comparably independent of the cluster size and the cluster-substrate-interaction. (Orig.)