Electron-phonon effects in 4d metals: calculation of coupling constant and resistivity

Abstract

A simple technique for calculating the phonon-limited resistivity ( rho _ph) of metals is described which is analogous to the Gaspari-Gyorffy method (1972) for calculating the electron-phonon coupling constant ( lambda ), rho _ph and lambda are calculated for all 4d metals and silver. The HCP metals have been treated as cubic, as is common in calculations of lambda . For rho _ph, however, this approach turns out to be too rough because it depends strongly on the average Fermi velocity which is very sensitive to crystal structure. In all transition metals investigated the superconducting and transport electron-phonon coupling constants are nearly equal, lambda approximately= lambda _tr. Also nearly equal are their electronic parts, eta approximately= eta _tr. The only exception is Pd, where eta _tr is nearly 1.5 times larger than eta ; this is because the superconducting and transport properties of Pd are defined by different parts of the Fermi surface. Palladium is the only 4d metal where the Mott model of conductivity (s-d scattering) is valid.