High-field susceptibility and the spin-wave spectrum of Fe 40Ni 40P 14B 6-alloys

Abstract

In amorphous Fe 40Ni 40P 14B 6-alloys, we have investigated the temperature and the field dependence of the law of approach to ferromagnetic saturation. Bloch's T 3 2 -law was found to be valid below 1 2 T c and the parasusceptibility followed an H - 1 2 -law. The spin-wave stiffness constant, D, of the spin-wave dispersion law, ϵ k = D k 2, was found to be D = 78 meV Å 2. Furthermore, an A/H 2-term in the susceptibility could be attributed to inhomogeneities in the microstructure of the amorphous state.