Effect of Pt buffer layer on structural and magnetic properties of FePt thin films

Ordered FePt thin films with face-centered-tetragonal (fct)-(001) preferred orientation have been prepared by magnetron sputtering a FePt layer onto a Cr91Ru9 underlayer. The effects of a Pt buffer layer between the CrRu underlayer and FePt layer on the structural and magnetic properties of the FePt films were investigated. The long range ordering parameter increases as the thickness of the Pt buffer layer increases from 0 to 4 nm. Further increase in the Pt buffer layer thickness (6 nm) causes the decrease of the ordering parameter. The out-of-plane coercivity of the films increases linearly with the increase of the thickness of the Pt buffer layer. Upon introduction of a 4 nm Pt buffer layer the number of defects in the FePt films are decreased drastically. The changes in the structural and magnetic properties of FePt films are related to the suppression of the Cr diffusion by the Pt buffer layer. (C) 2003 American Institute of Physics. [DOI: 10.1063/1.1531817].