The temperature variation of magnetization of bulk amorphous Ni₈₅P₁₅: An amorphous ferrimagnet?

Abstract

Abstract The variation of saturation magnetization with temperature of an Ni 85 P 15 alloy has been measured with the sample firstly in the as‐deposited amorphous state and secondly in a crystalline metastable single phase condition. The Curie temperature of the amorphous sample was roughly three quarters that of the crystalline form, and the saturation magnetization at absolute zero of the amorphous sample roughly one third that of the ordered form. The corresponding states curve of the amorphous alloy was appreciably below that of its crystalline state which, in turn, was lower than that normally observed in ferromagnetic materials. The results are interpreted in terms of a large distribution in exchange interaction between neighbouring nickel atoms such that a significant proportion of the exchange coefficients are negative; an assumption supported by other radial distribution data. The moments of those atoms whose interactions are predominantly negative will tend to lie antiparallel to those of the bulk of the material thereby accounting for the low saturation moment at absolute zero of the amorphous sample. The name amorphous ferrimagnetism is suggested for such a phenomenon.