Nanostructure and magnetic properties of polycrystalline FePdPt/MgO thin films

Atomic ordering, nanostructure and the magnetic properties of polycrystalline FePdPt thin films deposited with MgO underlayers have been investigated. The film thickness was fixed at 5 nm in all films, a thickness where perpendicular anisotropy is dominant. Films deposited at ambient temperature were postannealed at various temperatures to study the kinetics of atomic ordering. The Pd additions to FePt were effective in reducing the temperature needed for atomic ordering. The mean grain size determined by transmission electron microscopy is about 10 nm in annealed films. Within the limits of our observations, FePdPt films do not show phase separation into more than one phase of the L10 structure. The maximum coercivity (Hc) for annealed FePdPt films is about ∼3000–4000 Oe. In situ ordered FePdPt films at 530 °C show no indication of a lower temperature for atomic ordering.