Structure and Magnetic Properties of Graded (001)-Oriented FePt Films Prepared by Magnetron Sputtering and Rapid Thermal Annealing

L1(0)-FePt/[Fe/Pt](27) multilayer films were prepared on (100)-oriented single-crystal MgO substrates. Structural analysis indicates epitaxial growth of the L1(0)-FePt films during high-temperature deposition. The room-temperature-deposited [Fe/Pt](27) multilayer exhibits the fcc-FePt structure grown epitaxially on the L1(0)-FePt base layer. The degree of chemical order and thereby the anisotropy of the top layer has been controlled by varying the temperature of a post-deposition annealing process. Compared with the as-deposited films, coercivities of the films annealed below 400 degrees C are substantially decreased by introducing the formation of a graded anisotropy in the partially ordered top layer. Coercivities decrease for annealing temperatures that are greater than 400 degrees C due to improved ordering of the top layer.