Hyperfine field distribution in amorphous (FexNi1-x)80P14B6

Abstract

The magnetic hyperfine field distributions (P(H)) of amorphous (FexNi1-x)80P14B6 have been measured by 57Fe Mossbauer spectroscopy. The saturation P(H) and their concentration dependences have been determined using a Fourier series method. The reliability and shortcomings of this method are illustrated. For all samples of (FexNi1-x)80P14B6, the P(H) are well defined, single-maximum and asymmetric functions of H with a higher population at the low-field side. The P(H) shifts toward smaller H values for samples with decreasing Fe content, but the extrapolated P(H) for dilute Fe in amorphous Ni80P14B6 remains finite. The shape of P(H) is found to be insensitive to the Fe content and practically temperature-independent. For amorphous Fe80P14B6, the ratio of the average hyperfine field and the average magnetic moment is 150 kOe/ mu B, which is essentially the same as those observed in a large number of crystalline Fe metalloid compounds. This suggests that the Fe hyperfine field is likely to be proportional to its moment, due to a negligible conduction electron contribution. An appreciable amount of Fe atoms in samples with x>or approximately=0.3 has been found to have hyperfine fields larger than 340 kOe, the saturation value of alpha Fe.