Electron-phonon scattering in copper and silver from radio-frequency size effect measurements

The electron-phonon scattering rates vep(T) of electrons on extremal belly orbits perpendicular to the (111) and (100) directions have been measured between 0.5 and 8 K in Cu and Ag. Departures from the usual T3 regime are attributed to the changing effectiveness of the electron scattering with temperature and to the energy dependence of the electron-phonon scattering rate. Simple models including these effects describe the experimental data very well over the whole temperature interval and explain discrepancies between previous measurements performed on samples of different thickness. The results are consistent with data from transverse electron focusing and surface Landau level experiments.