Structural and magnetic properties of nanostructured FePt/MgO granular films

Fe/Pt/MgO multilayer films were deposited by magnetron sputtering on silicon substrates at room temperature, followed by rapid annealing under vacuum. Both as-grown FePt and annealed films showed a (111) preferred orientation. For the samples post annealed at 500 °C for 30 min, both the in-plane and the out-of-plane coercivities of the FePt films decreased with increased MgO layer thickness, while the coercivities of the FePt films increased with increased MgO layer thickness when the samples were annealed at 600 °C for 60 min. By annealing the as-deposited films at 600 °C for 60 min, the nanostructured FePt/MgO films consisting of the FePt grains with L10 structure embedded in the MgO matrix were obtained. The exchange coupling and grain size of the FePt decreased with increasing MgO layer thickness.