Magnetic Properties of Amorphous Fe-Nd Alloys

Single amorphous phase was obtained in Fe1−xNdx alloys by melt-spinning in a composition range of 0.11≤x≤0.60. Magnetization and Mössbauer effect were measured for these alloys.The internal magnetic field of 57Fe nuclei is about 2.4 MA/m(300 kOe) at 77 K, being independent of composition. It suggests that the average magnetic moment of Fe atoms is nearly constant: \barμFe\simeq2.0 μB/atom. On the contrary, the average magnetic moment of Nd atoms, calculated from the results of the magnetization measurements and the above estimation of \barμFe, decreases with increasing Nd concentration: \barμNd=3.2 μB/atom at x=0.15, which agrees with the free Nd3+ ion moment of 3.3 μB/atom and \barμNd=1.6 μB/atom at x≥0.40. While the coercive field, Hc, at 4.2 K is about 160 kA/m(2 kOe) for x=0.20, it increases abruptly for x>0.25 and becomes 5.6 MA/m(70 kOe) for x=0.55. These results can be explained by large random magnetic anisotropy of Nd atom in the amorphous alloys.