Magnetism of size selected, deposited transition metal and alloy clusters

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Clusters may experience strong modifications with respect to their intrinsic properties when being in contact with a surface. Electronic structure relaxation may particularly modify the magnetic moments in transition metal clusters, since they are directly connected with the electronic configuration of the open 3d shell. In addition, the interaction with the substrate may lead to an effective magnetic cluster cluster interaction, giving rise to super-ferromagnetism. The experiment proposed here are concerned with these two specific aspects of interactions between mass selected magnetic clusters and solid surfaces. The high sensitivity of x-ray magnetic circular dichroism will be exploited to study the magnetic properties clusters deposited in situ. The evolution of the magnetic moments in binary alloy (FePt,CoPt) clusters will be studied as a function of atomic composition, which can be precisely chosen by mass selection at small cluster sizes. Likewise, the effect of alloying on the magnetic sensitivity to surface interaction will be specifically studied. Effective magnetic cluster cluster interactions will be studied for the system Fen/Cu(111) to elucidate the mechanism behind the high critical temperatures and strong magnetic anisotropies reported for this class of systems. Here, we will explore both, the dependence on particle size and the preparation method (cluster deposition versus cluster formation in rare gas layers), respectively.