Low-temperature specific heat and superconductivity ofα-phaseAu−Gaalloys

Abstract

Low-temperature specific-heat measurements are reported on $\alpha$-phase $Au-\mathrm{Ga}$ alloys. The electronic specific-heat coefficient $\gamma$ is observed to increase upon alloying at the initial rate $\frac{d\ln \gamma }{\mathrm{dz}}=0.95\mathrm{}$. The Debye temperature is observed to decrease in the alloys at the rate - 1.63 K/at.%. The increase in $\gamma$ is compared with increasing values of $\lambda$, the electron-phonon mass enhancement as evaluated from measurements of the superconducting transition temperature. Comparison is also made between the values of $\gamma$ and $\lambda$ for $Ag-\mathrm{Ga}$ and $Cu-\mathrm{Ga}$ $\alpha$-phase alloys. We find that the band-structure density of states at the Fermi level, $N_{\mathrm{bs}}$ for $Au-\mathrm{Ga}$ and $A\mathrm{g}-\mathrm{Ga}$ alloys is a weakly increasing function of composition, while for $Cu-\mathrm{Ga}$ alloys it is slightly decreasing and in good agreement with the calculations of Lasseter and Soven.