CHARACTERIZATION OF EPITAXIALLY GROWN FE-N FILMS BY SPUTTER BEAM METHOD

We have prepared epitaxial Fe-N martensite (alpha') films on alpha-Fe (001) single-crystal underlayers by the sputter beam method and synthe sized a metastable alpha ''-Fe16N2 phase by post-annealing. The satura tion magnetization (4 pi M(s)) of the alpha' phase films is in the ran ge of 21.9-23.3 kGauss which is larger than that of alpha-Fe. Magnetiz ation of the annealed samples containing alpha ''-Fe16N2 phase have in creased with the x-ray diffraction intensity ratio of alpha ''(002) to [alpha ''(004)+alpha'(002)]. Very careful analysis of x-ray diffracti on data gives more reliable value on the volume fraction of the alpha '' phase in the annealed samples. As a result, it is found that the Fe -N film with magnetization of 24.7 kG contains 32 vol %-alpha '' phase within it. This result leads us to believe that alpha ''-Fe16N2 phase has a remarkably large saturation magnetization. (C) 1996 American In stitute of Physics.