Finite Temperature Correlations on Plasmon and Coulomb Drag in Coupled Quantum Wells

We calculate the temperature dependence of correlations in coupled quantum wells using an STLS formalism generalized to Þnite temperatures. We investigate the e¤ects of the temperature dependence of the correlations on the acoustic and optical plasmon dispersion curves and on Coulomb drag. Correlations are known to depress the energies of the two plasmons, while Þnite temperatures tend to increase the energies. We Þnd this can result in considerable cancellation between the two e¤ects at Þnite temperatures. We Þnd that at temperatures kBT<EF the local fields do not change appreciably with temperature so that in calculating the temperature dependence of the Coulomb drag using the zero temperature local fields suffices. The pair correlation function within the layers is also found to be insensitive to temperatures for kBT<EF. For higher temperatures than this the pair correlation function for small separations starts to increase as the exchange-correlation hole shrinks.