Kerr effect of ordered and disordered Fe/sub 1-x/Pt/sub x/[001] alloy films

The [001) oriented Fe/sub 1-x/Pt/sub x/ alloy films have been grown on Pt seeding layers on MgO[001] substrates by MBE. At growth temperature of 500/spl deg/C, rather ordered structures were formed for FePt, FePt/sub 2/, and FePt/sub 3/ films, which exhibit large perpendicular magnetic anisotropy and Kerr rotations. In contrast, Fe/sub 2/Pt and Fe/sub 3/Pt films were poorly ordered and did not display perpendicular magnetization for similar growth conditions. The optimal growth temperature of the FePt (x=0.5) alloys occurs at about 500/spl deg/C, and the surface order-disorder transition occurs above 650/spl deg/C. We demonstrate that chemical ordering is important for perpendicular magnetic anisotropy and Kerr effects for Fe/sub 1-x/Pt/sub x/ alloy films, which in turn depend strongly on the alloy composition and growth temperature.