Magnetic Properties and Microstructure of Exchange Coupled (FePt-Fe)/(Ag-FePt) Films

A soft/hard chemically disordered/ordered (FePt-Fe)/(Ag-FePt) films was prepared on a glass substrate. The (FePt-Fe)/(Ag-FePt) film was exchange coupled and annealed (FePt-Fe)/(Ag-FePt) film again from 200 to 700 for 1 min allowed modification of the interface from sharp to rough and finally into graded. The (FePt-Fe)/(Ag-FePt) films annealed from 200-600 show two-steps out-of-plane magnetization curves. The magnetization of disordered FePt-Fe reversed first and followed by the ordered Ag-FePt film. When the film annealed at 700, the out-of-plane magnetic hysteresis loops show perpendicular anisotropy with rigid magnetization which was due to the nanoscale interface exchange coupling. The magnetization was reversed at a single switching field and interpreted by the two-spin model. The exchange coupled composite film with perpendicular magnetization can be performed in the chemically disordered/ordered FePt system.