Perpendicular magnetic anisotropy and spin reorientation transition in L1 FePt films

We investigated the thickness and composition dependence of perpendicular magnetic anisotropy (PMA) in L10 Fe1−xPtx (x = 0.4, 0.5, and 0.55) films. The FePt films with different thicknesses of 35 and 70 Å were grown at the substrate temperature Ts = 300 °C by molecular beam epitaxy coevaporation technique. A (001)-oriented epitaxial L10 FePt film was grown on the thin (001)-oriented fcc Pt layer, while a poorly crystallized FePt film was formed on the (111)-textured Pt layer. Our results showed that, at a fixed thickness of 70 Å, the PMA of FePt alloy films is enhanced as Pt content increases from 40% to 55%.