Magnetic, transport, and structural properties of iron-platinum thin films

The magnetic, transport, and structural properties of RF sputtered Fe-Pt thin films were studied as a function of Pt content from 0 to 75 at.%. Polycrystalline ferromagnetic films were obtained in the range studied. The properties of the films are very similar to those obtained for bulk alloys. A body-centered-cubic phase is obtained for as-deposited films with less than 25 at.% Pt, and a face-centered-cubic structure is obtained for films with more than 25 at.% Pt. By annealing equiatomic Fe-Pt films, very large coercivities (about 10 kOersteds) can be obtained depending on the thickness, duration and temperature of annealing. The magnetization of Fe-Pt films is sufficiently large such that a moment of approximately 0.4 Bohr magneton must be associated with the Pt if Fe remains at 2.2 Bohr magneton per atom. The magnetostriction, Hall effect, and anisotropic magnetoresistance are all large near the equiatomic range of compositions.