Hard Magnetic FePt Thin Films and Nanostructures in L10 Phase

By using high-resolution transmission electron microscopy the formation of the L10 phase in Fe-Pt multilayer can be studied in-situ during annealing. The formation of L10-FePt nuclei starts in the Pt layers by diffusion of Fe into the Pt layers. During annealing the L10-FePt nuclei grow in size and expand over the whole film. By using electron lithography patterned L10-Fe54Pt46 nanostructures have been produced. Below a critical dot thickness during post-annealing at high temperatures the dots split into an accumulation of isolated (single-domain) particles of irregular shape resulting in large coercivities of μ0Hc = 2.4 T.