Dispersion of two-dimensional plasmons in GaAs quantum well and Ag monolayer

Abstract

We study theoretically the role of finite temperature, exchange-correlations and finite layer width in explicating experimental findings on dispersion of two-dimensional plasmons in GaAs single quantum well and Ag monolayer. The plasmon energy is obtained from the poles of electron density response function determined by using the finite-temperature self-consistent mean-field theory of Singwi et al. Except for ultra low electron densities (as in GaAs system), our results exhibit a reasonably good agreement with the experimental data. While correlations are found to introduce a noticeable red shift in plasmon frequency, temperature has an opposite effect. Both of these effects become increasingly important with reduction in electron density. At ultra low densities, our predictions agree only for small wave vectors (q<0.6kF), with correlations over-suppressing plasmons into the single electron–hole pair continuum already at a relatively small q. This shortcoming may be arising due to the neglect of the dynamical nature of correlations in our study. Further, it is found that finite layer width gives rise to a red shift in plasmon dispersion, but its effect is significant when average electron-electron spacing is smaller than or comparable with layer width.