Annealing Effects on Magnetic Properties of Co/Pt Multilayers

Co/Pt multilayer films sputter-deposited with and without a substrate bias of VB=¿30 V were annealed in vacuum at 300 and 400°C. On annealing the saturation magnetization Ms and the saturation Kerr rotation angle ¿K both increased, while the perpendicular anisotropy energy Ku decreased monotonically. The decrease in Ku was larger for ¿30 V biased films than for 0 V films because of the larger decrease in the surface anisotropy Ks for ¿30 V biased films. This larger decrease in Ks is discussed taking the relaxation of lattice strain due to annealing into account.