Low-temperature ordering of L1(0)-CoPt thin films promoted by Sn, Pb, Sb, and Bi additives

We have studied the effect of additional elements of Sn, Pb, Sb, and Bi on the ordering of L1(0)-CoPt films. All of these additives are demonstrated t o be very effective to promote the ordering and developing of a very large coercivity of the samples annealed at 400 degreesC. It is worth noting that this annealing temperature for ordering is 200 degreesC lower than that of pure CoPt. The crystallographic and chemical analyses have revealed that t hese additives easily diffuse and segregate onto the film surfaces by posta nnealing because of their very low surface free energy and extremely low so lubility in Co. Therefore, it seems reasonable to conclude that the orderin g in the CoPt film is significantly promoted at much lower temperature by t he aid of a lot of defects produced by the additives excreted by postanneal ing. (C) 2001 American Institute of Physics.