Low-Temperature Specific Heats ofAgAuAlloys

Abstract

The specific heats of solid solutions of up to 40 at.% Au in Ag have been measured between 2 and 4°K. The electronic specific heat coefficient $\gamma$ decreases on adding Au to Ag at the initial rate of about -30% per unit concentration, reaching a minimum value at about 20% Au. This result disagrees sharply with scattering theories proposed to account for the increase of $\gamma$ upon alloying noble metals with $b$-subgroup solutes. In view of other evidence that wave functions for both pure Au and Ag have the same symmetry near the necks of the Fermi suface, our result disagrees with either "rigid" or "soft" band-structure interpretations. The Debye temperatures of the alloys are slightly greater than those expected from linear interpolation between those of the pure metals.