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

Abstract

The magnetic hyperfine field distributions (P(H)) of amorphous (Fe_xNi_1-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 (Fe_xNi_1-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.