CoPt:B granular thin films for high density magnetic recording media

Granular CoPt: B films, consisting of high anisotropy, face centered tetragonal (FCT) CoPt particles embedded in a B matrix have been successfully prepared. Their structural and magnetic properties are investigated as a function of annealing temperature and boron content, to examine their suitability for magnetic recording media. Grain size and isolation can be adjusted by the boron concentration and annealing process: boron is found to lower the required processing temperature. A minimum grain size is obtained for the 20 vol% B samples for all annealing temperatures. The activation volume as estimated by magnetic relaxation and remanence measurements approaches the physical particle size only for the nanocomposites with grain sizes below 20 nm, indicating a coherent rotation mechanism in these dims. (C) 2001 Elsevier Science B.V. All rights reserved.