Low-temperature properties of amorphous (Mo1−x Ru x )0.8P0.2 alloys

Amorphous (Mo1−x Ru x )0.8P0.2 alloys (0.3≤x≤0.7) have been investigated with measurements of the specific heatC and thermal conductivity κ. Also the superconducting properties (critical temperatureT c and upper critical field) have been determined. Well belowT c , all alloys show the familiar behavior known for glasses, i.e.C∼T n and κ∼T m withn≈1 andm≈2 which is attributed to tunneling states (TLS). The largeT c allows an unambiguous determination of the coefficients ofC and κ. Compairing our data with literature data, we find no correlation between the TLS density of states and the glass temperature or crystallization temperature, as opposed to insulating glasses where such a correlation appears to exist. The unusual annealing behavior found previously in amorphous Zr−Ni and Zr−Cu, which was attributed to a change in the TLS relaxation-time spectrum, is confirmed in the present work.