Interplay between local structure and magnetic properties of graded exchange-coupled Co@FePt nanocomposite films

International audienceMagnetically-hard nanocomposites are attractive materials for integration in various microsys-tems and for building next generation permanent magnets. However, exploiting their full potential requires to control their microstructure at the nanometre scale. Studying these materials in model systems synthesised by nanofabrication routes gives interesting insights about 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 have prepared 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 polarisation dependent hard X-ray absorption spectroscopies. These results demonstrate that magnetically soft inclusions are stabilised at room temperature, emphasising the role of the interdiffusion in the preparation of nanocomposites