Dynamic correlations in double-layer electron systems

Abstract

We study the effects of dynamic correlations on the ground-state properties of a double-layer two-dimensional electron gas within the quantum Singwi-Tosi-Land-Sjölander theory (STLS). The intralayer and interlayer static structure factors, the pair-correlation functions, and the wave vector and frequency-dependent local-field factors have been calculated for a range of electron densities and layer separations. We find that the local-field factors have an oscillatory frequency dependence and the magnitude of interlayer local-field factors is about an order of magnitude smaller than that of the intralayer. Our results are compared with the random-phase approximation and the static STLS approximation to assess the importance of dynamical correlations. We also calculate the dispersion relations for the optical and acoustic plasmons and the damping of these modes to compare them with other mean-field theories, and we comment on the relevance of our results to the recent experiments.