Effects of os inserted layers on the structures and magnetic properties of the FePt film

Spacer layer effect on multi-layer [FePt/Os]_n films has been investigated from the variation of magnetic properties and microstructure of the films. From a HRTEM cross-section view observation, the Osmium (Os) underlayer and space layers can effectively prevent the diffusion of Si atoms and the intermixing between FePt layers induced by annealing process, respectively, even annealing temperature higher than 700°C. Selected area diffraction pattern indicated that the structure of Os spacer layer was amorphous. The average grain size of the multilayer films can be well controlled by both annealing temperature and thickness of the FePt layers. The average grain size of [(FePt)x/Os]_n films is roughly 18 nm for x = 20 nm, n = 5, that is smaller than the average grain size of single layer FePt films (70 nm). The multilayer [(FePt)x/Os]_n films with Os as the spacer exhibit good hard magnetic properties and are attractive candidates for ultrahigh density magnetic recording media.