Low-temperature specific heat of the 'nearly ferromagnetic' amorphous alloy Y0.22Ni0.78

Abstract

The authors report the results of specific heat measurements, between 0.3K and 10K, in magnetic fields up to 75 kOe, on the 'nearly ferromagnetic' amorphous alloy Y_0.22Ni_0.78. The results, especially the magnetic field dependence, exclude any appreciable contribution from uniform paramagnons. In contrast a quantitative analysis is obtained in terms of superparamagnetic clusters, demonstrating that the onset of ferromagnetism, as a function of concentration, is inhomogeneous in this amorphous metallic system.