High energy products in exchange-coupled nanocomposite films

Several systems of nanocomposite thin films have been prepared by plasma sputtering and heat treatment. By choosing suitable multilayer structures of the as-deposited films and subsequent heat-treatment processes, the nanostructures of the films have been tailored. The thermal processing is the key to control the morphology. Appropriate heat-treatment processes have been found for the systems studied, which result in the desired nanostructures. For the first time a nearly ideal nanostructure with the soft-phase grains embedded homogeneously in the hard phase grains has been obtained for the FePt-Fe1-xPtx(x similar to 0.3) system. Effective intergrain exchange coupling has been realized. As a consequence, high energy products up to 50 MGOe have been achieved.