Low-temperature resistivity and thermoelectric ratio of copper and gold

Abstract

The resistivity $\ensuremath{\rho}$ and thermoelectric ratio $G$ have been measured between 0.04 and \ensuremath{\sim}7 K for "pure" polycrystalline samples of copper and gold, in a dilution refrigerator with a superconducting quantum-interference device null detector system. The measurements confirm that these metals, like silver, show a $\ensuremath{\rho}\ensuremath{-}{\ensuremath{\rho}}_{0}\ensuremath{\propto}{T}^{4}$ temperature dependence over a substantial temperature range. For the best copper sample a $\ensuremath{\rho}\ensuremath{-}{\ensuremath{\rho}}_{0}\ensuremath{\propto}{T}^{2.03}$ temperature dependence below 2 K is strong evidence for electron-electron scattering.