Magnetic Properties of Sputtered CoPt Films

CoPt alloy films have been prepared by RF sputtering. Film thickness is 100 nm and saturation magnetization Ms ranges from approx 600-1300 emu/cm exp 3 . In films prepared without substrate bias, the easy axis of magnetization lies in the film plane irrespective of Ms. However, perpendicular anisotropy is greatly enhanced by resputtering. In films prepared with the substrate bias of --80 V, the easy axis is perpendicular to the film plane, provided that Ms is within the range from approx 800-1000 emu/cm exp 3 . Perpendicular anisotropy in a resputtered film is greatly reduced by annealing in vacuum, while there is no significant difference between X-ray diffraction patterns before and after annealing. In films prepared without substrate bias, perpendicular coercivity is almost the same as in-plane coercivity, taking a maximum value of approx 1.4 kOe when Ms approx = 950 emu/cm exp 3 . Perpendicular coercivity is hardly affected by resputtering, while the maximum of in-plane coercivity is somewhat reduced by resputtering. Graphs, Diffraction patterns. 5 ref.--AA