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 approximat ion (RPA) at finite temperature is employed to describe the effective interlayer Coulomb interaction. The electron-electron and electron-opt ical phonon couplings are treated on an equal footing. The electron-ph onon mediated interaction contribution is investigated for different l ayer separations and layer densities. We find that the drag rate at hi gh temperatures (i.e., T greater than or equal to 0.2E(F)) is dominate d 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 inc rease in magnitude, compared to the uncoupled system results in RPA. T his behavior is in qualitative agreement with the recent measurements. Including the local-field effects in an approximate way we also estim ate the contribution of intralayer correlations.