Magnetic properties and microstructure of graded Fe/FePt films

A soft/hard Fe/FePt bilayer with perpendicular magnetization was prepared on a glass substrate. Annealed Fe/FePt film allowed modification of the Fe/FePt sharp interface to Fe/(Fe-rich FePt)/FePt graded interface with rigid magnetization due to the nanoscale soft/hard interface coupling. The magnetization was reversed at a single switching field and interpreted by the two-spin model. When the annealed temperature of the Fe/FePt film increased, the remanence magnetization decreased continuously but the out-of-plane coercivity increased obviously at 600-700 degrees C which was interpreted by the graded magnetic anisotropy. The coercivity can be tuning in the exchange coupled composite film. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3446198]