EVIDENCE OF A SURFACE-MEDIATED MAGNETICALLY INDUCED MISCIBILITY GAP IN CO-PT ALLOY THIN-FILMS

(100) and (111) oriented single-crystal CoPt3 films were deposited ove r a range of growth temperatures from -50 to 800 degrees C. The Curie temperature is increased by 200 degrees C over the value expected for the homogeneous alloy in the as-deposited films (of both orientations) grown near 400 degrees C. We interpret this as evidence for a previou sly unobserved, surface-mediated, magnetically driven miscibility gap in vapor-deposited CoPt3 films. Large perpendicular magnetic anisotrop y is also observed in the as-deposited films (of both orientations) gr own near 400 degrees C.