Steering the magnetism of low-dimensional Fe-Pt nanostructures through coordination

A complete understanding is still missing. All models, however, emphasize the importance of Fe-Pt coordination and the induced moments in Pt-atoms for the magnetic anisotropy and the formation of an effective exchange field. We recently performed XMCD measurements on a Fe50Pt50 monolayer alloy grown on vicinal Pt(997). The surface alloy exhibits high coercive fields comparable to those found in 3D samples exhibiting L10 structure. These results suggest that, in contrast to theoretical work, the third dimension in the L10-phase is not necessarily the key for the understanding of its hard magnetic properties. We therefore studied the magnetism of low-dimensional Fe structures as a function of Fe-Pt as well as Fe-Fe coordination.