MAGNETIC-PROPERTIES AND MICROSTRUCTURE OF IRON PLATINUM THIN-FILMS

The microstructure and magnetic properties of sputtered Fe-Pt thin films were studied as a function of Pt content from 0 to 60 at%. Polycrystalline ferromagnetic films were obtained in the range studied. A mixture of body-centered-cubic and disorder face-centered-cubic (gamma) phases was obtained for as-deposited films with less than 22 at% Pt, and a disorder face-entered-cubic (gamma) structure was obtained for films with more than 33 at% Pt. By annealing films containing about 33 at% Pt, a coercivity of 13 kOe could be obtained depending on the duration and temperature of annealing. An order faced-centered tetragonal (gamma1) phase appeared under suitable treatment in the samples containing 22 to 50 at% of Pt. For films comprising about 60 at% Pt, annealing treatment made the magnetic properties to deteriorate owing to the formation of an antiferromagnetic phase (fcc, Ll2-type). X-ray analysis and microstructure observations revealed that the magnetic hardening was caused by changing the ordering from the gamma to the gamma1 phase.