Effect of Ag segregation on reversal behavior of [(FePt).sub.77] [Ag.sub.23] alloy thin films

Effect of Ag segregation on magnetic and structural properties of [(FePt).sub.77] [Ag.sub.23] single-layer films were studied. Thin films were first sputtered on the heated glass substrates and cooled to room temperature, a post annealing at temperatures ([T.sub.p]) from 200 [degrees]C to 400 [degrees]C for 60 min was then applied. [L1.sub.0] structure formed as substrate temperature ([T.sub.s]) equals to 600 [degrees]C and 700 [degrees]C. For those ordered films, Ag was observed to precipitate as particles on the film surface and grow with the increasing [T.sub.s]. After post annealing at 400 [degrees]C for 60 min, those silver particles dissolved into the film, leading to changes in reversal behavior. The optimum condition is obtained in the [T.sub.s] = 600 [degrees]C, [T.sub.p] = 400 [degrees]C sample. Drastic reduction in coercive squareness ratio (from >0.8 to 0.41) and enhanced coercivity (from 4.7 to 6.4 kOe) indicate the reversal behavior alters from cooperative to independent. Negative [delta]M curve suggests that this independent rotation results from the reduction of exchange interactions. Index Terms--Coercivity enhancement, domain structure, FePt, reversal behavior, segregation, thin film.