The effect of annealing on [001] FeTaN heteroepitaxial films

The position of the nitrogen in [001] oriented FeTaN epitaxial thin films prepared on [001] MgO by reactive sputtering in an Ar-N atmosphere was determined by X-ray diffraction and its mobility investigated by annealing experiments. Lattice spacing measurements of the [002], (011), (211) and (112) crystallographic planes revealed that the bcc FeTa lattice with the inclusion of nitrogen underwent a tetragonal deformation with the c-axis out of the sample plane and with a maximum tetragonality in these samples of /spl sim/1.02. Upon annealing for two hours between 250/spl deg/C and 650/spl deg/C, the [002] lattice spacing and the crystalline anisotropy changed back to the values measured in nitrogen free films. No change in the magnetization was observed with annealing. The fact that the nitrogen occupies the interstitial sites in the z-direction perpendicular to the film plane may explain the relative insensitivity of magnetic properties measured in the [001] plane to the nitrogen concentration.