Energy relaxation times in metal films from the response of electrical conductivity to periodic heating

Abstract

Heating of a metal film with a weak oscillating heat source leads to oscillations of the electron temperature ${T}_{e}$. Because of the temperature dependence of phonon contribution to electrical conductivity, the oscillations of ${T}_{e}$ result in oscillations of voltage across the current-carrying film. Using the equation for ${T}_{e}$ and the expression for the phonon contribution to the electrical conductivity, we have found the connection of the frequency dependence of the amplitude of the voltage oscillations across the film with the time of electron-phonon collisions (${\ensuremath{\tau}}_{e}$) and the mean phonon escape time from the film to the substrate (${\ensuremath{\tau}}_{es}$). Renormalization of electron-phonon interaction by impurities and defects is considered phenomenologically. It is discussed how the times ${\ensuremath{\tau}}_{e}$ and ${\ensuremath{\tau}}_{es}$ can be found experimentally using the peculiarities of the frequency dependence of the voltage oscillations across the film.