Effect of Axial Ratio and Atomic Volume on Magnetism of and -Fe–N

alpha´ (bct) and gamma´(fct)-Fe-N with various N contents and unit-cell volumes were synthesized by using a multilayer fabrication technique. The effect of axial ratio and atomic volume on magnetism of these phases was examined. The atomic volume of alpha´ and gamma´ phases monotonously increases with increasing either N content of Fe-N layers or in-plane lattice spacing of intermediate layers. In both cases of alpha´ and gamma´-Fe-N, the magnetic moment increases with increasing atomic volume. This result qualitatively corresponds to theoretical prediction. In the case of alpha´-Fe-N, the magnetic moment increases with an increasing axial ratio. On the other hand, in the case of gamma´-Fe-N, the magnetic moment decreases with an increasing axial ratio. In the case of alpha´-Fe-N, the exchange integral (J) does not change against both atomic volume and axial ratio. On the other hand, in the case of gamma´-Fe-N, J increases with increasing atomic volume and slightly decreases with increasing axial ratio. Judging from these results, we can expect to further enhance the magnetic moment with relatively high T_c, when we could realize the intermediate state of alpha´ and gamma´-Fe-N