Interplay Between Local Structure and Magnetic Properties of Graded Exchange-Coupled Co@FePt Nanocomposite Films

Hard magnetic nanocomposites are attractive materials for integration in various microsystems and for building of next-generation permanent magnets. However, exploiting their full potential requires control of their microstructure at the nanometer scale. Studying these materials in model systems synthesized by nanofabrication routes provides interesting insights into the interplay between the microstructure and the magnetic performances. Here, by using a combination of mass-selected low-energy cluster beam deposition and electron-beam evaporation, we prepare nanocomposite films where Co nanoinclusions are integrated in a hard magnetic FePt matrix. Local atomic structures and element-selective magnetic properties of such nanocomposites have been thoroughly investigated using polarization-dependent hard x-ray absorption spectroscopies. These results demonstrate that magnetically soft inclusions are stabilized at room temperature, emphasizing the role of interdiffusion in the preparation of nanocomposites.