Coulomb pseudopotential for superconducting alloys from the normal-state resistivity

The Coulomb pseudopotential ${\mu }^{*}$ is estimated from the superconducting $T_c$ and the normal-state resistivity-temperature derivative, $\frac{d\rho }{\mathrm{dT}}$. This method is applied to noble-metal alloys. New resistivity measurements for AuAl and AgGa alloys as a function of temperature and concentration are presented. Analysis of these data and published results for $T_c$ and $\frac{d\rho }{\mathrm{dT}}$ give ${\mu }^{*}=0.125\mathrm{}\pm 0.009$ for three alloy systems. $T_c:s$ for pure Au and Ag are also estimated. For Au the result is about ${10}^{-4\mathrm{}}$ K while $T_c$ for Ag is nonzero but exceedingly low. The electron-phonon interaction $\lambda$ is obtained from $\frac{d\rho }{\mathrm{dT}}$ in $n\Omega$ cm/K by $\lambda =0.0312\mathrm{}$ $\frac{d\rho }{\mathrm{dT}}$ to an accuracy of 0.01 for noble-metal alloys.