The effects of Ag underlayer and Pt intermediate layers on the microstructure and magnetic properties of epitaxial FePt thin films

In this work, Ag underlayers, which have a slightly larger lattice parameter than FePt, were found not only to induce epitaxial growth of the FePt films but also to reduce the temperature at which the atomic ordering occurred. Without using the Ag underlayer, the FePt film deposited onto the hydrofluoric acid etched-Si substrate was FCC disordered. When Ag underlayers were used the FePt unit cells were expanded in the film plane. This caused the shrinkage of the FePt unit cells along the film normal direction and resulted in the in situ ordering of the FePt thin film at reduced temperatures. Furthermore, it was found that the degree to which the FePt unit cells contracted along the film normal varied when a Pt intermediate layer was added. This resulted in FePt thin films with different textures and magnetic properties. The microstructural and magnetic properties of the FePt films prepared at various substrate temperatures, FePt thicknesses, Ag underlayer thicknesses and with the use of the Pt intermediate layer were studied to investigate the L10 FePt ordering. r 2002 Published by Elsevier Science B.V. PACS: 75.70. i; 75.75.+a