Coupled plasmon-phonon mode effects on the Coulomb drag in double-quantum-well systems

We study the Coulomb drag rate for electrons in a double-quantum-well structure taking into account the electron-optical phonon interactions. The full wave vector and frequency dependent random-phase approximation (RPA) at finite temperature is employed to describe the effective interlayer Coulomb interaction. The electron-electron and electron-optical phonon couplings are treated on an equal footing. The electron-phonon mediated interaction contribution is investigated for different layer separations and layer densities. We find that the drag rate at high temperatures (i.e., T≥0.2EF) is dominated by the coupled plasmon-phonon modes of the system. The peak position of the drag rate is shifted to the low temperatures with a slight increase in magnitude, compared to the uncoupled system results in RPA. This behavior is in qualitative agreement with the recent measurements. Including the local-field effects in an approximate way we also estimate the contribution of intralayer correlations.