Magnetic properties and microstructure of Fe-Pt-based alloys

Fe-Pt-based alloys with small amounts of Nb and Al doping were prepared by arc melting. The effects of the heat treatment and the third element on the hard-magnetic properties of the alloys were studied. We observe domains with sizes from 1 to 20 nm, depending on the thermal history. We attribute the significant remanence enhancement to an exchange coupling between nanosize single-domain particles with face-centered tetragonal structure and the fcc matrix.