Low-temperature Ordering in FePt Films Deposited by Gas Flow Sputtering

概要

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FePt films were deposited by a low energy sputtering method, i.e., gas flow sputtering, without heating the substrate. The effects of annealing on the L10 order parameter, morphology, and magnetic properties of the films were studied. The order parameter increased significantly after annealing at 413°C; the order parameter of a 76-nm-thick film was found to be 0.84. The coercivity of the film was 15.6 kOe, which was in agreement with the high order parameter. Scanning electron microscopy observations showed that the ordering in the films proceeded with the growth of grains. The XRD pattern of an unannealed thick (950 nm) film showed a 110 superstructure peak. The small grain size in the as-deposited film and the existence of nuclei of the L10 phase may play key roles in inducing the ordering at a relatively low temperature. These factors may promote discontinuous ordering, wherein ordering proceeds with grain boundary diffusion and growth of grains with an L10 structure.
2009-05-01