Effects of annealing on the magnetic properties and structures of sputtered Co-Pt alloy thin films

The effects of annealing on the in-plane coercivity and the crystal structu re have been investigated for sputtered Co-Pt alloy thin films with Pt cont ent between 0 and 50 at.%. The coercivity of a Co50Pt50 film drastically in creases at annealing temperatures above 800 K. The coercivity increase corr esponds to the formation of an L1(0) ordered phase, which is formed by the annealing at 940 K in less than 1 h. A maximum coercivity of 920 kA/m (11.5 kOe) is more than that reported for a bulk Co-Pt alloy. The grain size dra stically increases in the early stage of annealing. (The grain size should be decreased for the use of the Co-Pt films as high-density recording media .).