ANNEALING EFFECT OF EQUIATOMIC CO/PT ALLOY-FILMS

Polycrystalline as-sputtered CoPt alloy films near the equiatomic composition were characterized as consisting of a disordered fcc phase with preferred texture along [111] orientation perpendicular to the film plane. The film annealing at 600-degrees-C/16 h induces the disorder-order phase transition confirmed by X-ray diffraction. As a result of the transition an appearance of the ordered tetragonal (fct) phase of AuCuI type with c/a = 0.974 is observed. The c-axis is the easy axis of magnetization. Both longitudinal and polar Kerr hysteresis loops reveal a dramatic increase in the coercivity from 0.1 to 4.5 kOe in annealed CoPt alloy films due to ordering.