Coulomb Drag as a Probe of Coupled Plasmon Modes in Parallel Quantum Wells

We show theoretically that the Coulomb drag rate between two parallel quasi-two-dimensional electron gases with equal Fermi velocities is substantially enhanced by the coupled acoustic and optic plasmon modes at temperatures T≳0.2TF (where TF is the Fermi temperature) for experimentally relevant parameters. The acoustic mode causes a sharp upturn in the scaled drag rate with increasing temperature at T≈0.2TF. Other experimental signatures of the plasmon-dominated drag rate are a d-3 dependence on the well separation d and a peak as a function of relative densities at matched Fermi velocities.