Effects of forming gas annealing on low-temperature ordering of FePt films

FePt Films with a large coercivity of as high as 7700 Oe were obtained after forming-gas annealing at 275 degrees C. The coercivity was further increased to 13500 Oe by annealing at 400 degrees C. Hydrogen atoms may occupy the interstitial sites of FePt, inducing a local strain or an agitation to accelerate the ordering of FePt. The (111) d-spacing of FePt depends not only on the degree of ordering but also on the amount of hydrogen atoms. The coercivity increased with the amount of hydrogen atoms dissolved in the FePt lattices. The coercivity of FePt films annealed in the forming gas also depended strongly on the thickness. (c) 2005 American Institute of Physics.