Evidence of a Surface-Mediated Magnetically Induced Miscibility Gap in Co-Pt Alloy Thin Films

(100) and (111) oriented single-crystal CoPt{sub 3} films were deposited over a range of growth temperatures from {minus}50 to 800 {degree}C. The Curie temperature is increased by 200 {degree}C over the value expected for the homogeneous alloy in the as-deposited films (of both orientations) grown near 400 {degree}C. We interpret this as evidence for a previously unobserved, surface-mediated, magnetically driven miscibility gap in vapor-deposited CoPt{sub 3} films. Large perpendicular magnetic anisotropy is also observed in the as-deposited films (of both orientations) grown near 400 {degree}C.