Magnetic properties of electron beam evaporated CoPt alloy thin films

A systematic study of magnetic properties of CoPt alloy thin films as a function of composition and substrate deposition temperature has been carried out. The concentration dependence of the intrinsic perpendicular magnetic anisotropy constant K/sub u/ at ambient temperature reveals a maximum at about 25 at% Pt. Films of Co/sub 75/Pt/sub 25/ deposited onto Al/sub 2/O/sub 3/ (0001) substrates held at temperatures from 180/spl deg/C to 400/spl deg/C exhibit a strong perpendicular magnetic anisotropy (1.5/spl times/10/sup 7/ erg/cm/sup 3/). This strong anisotropy is closely related to the ordered state of the hcp structure.