The influence of the Ag substrate on the structure and magnetic properties of FePt thin films

FePt-X/Ag(X=Ag or Pt) films have been deposited on natural-oxidized Si(100) substrates by magnetron sputtering.The structures,grain sizes,and magnetic properties were measured by XRD,TEM and VSM.A 20nm Ag underlayer was found to be favorable for improving the(001) preferential orientation.Ag agglomerated in as-deposited films,the grain size of annealed FePt films decreased as Pt content increased.X-ray diffraction measurements showed the FePt phase in the film that undergo a phase transformation from a disordered face-centered-cubic(fcc) phase to an ordered face-centered-tetragonal(fct) phase at 400℃.The coercivity of the annealed FePt alloy films was 1.04×10~6A/m,whiles average grain sizes was about 100 nm in sample annealed at 500℃.