Magnetic Surface Levels in Cu-Determination of Electron-Phonon-Scattering Rates

Using the surface-quantum-state resonances in Cu at microwave frequencies ∼35 GHz we have investigated the temperature dependence of the electron scattering rate in the range 2-25°K. From the temperature dependence we obtain the electron-phonon scattering rates of the resonant electrons. We describe the procedure in which we assign a value of the scattering rate to an experimental line shape, and consider how the value of the scattering rate thus obtained is related to a localized group of electrons on the Cu Fermi surface. The ten locations on the Fermi surface at which we have measured the thermal scattering rate are along the central zones of the (100) and (110) planes. We find a maximum-scattering-rate anisotropy of about a factor of 30, the highest rate being on the necks, and the lowest at the $〈110〉$ direction.