Exchange-correlation effects in coupled quantum wire systems at finite temperature

Abstract

We investigate the exchange-correlation effects in coupled quantum wire systems at finite-temperature within the self-consistent mean-field approximation of Singwi et al by assuming the charge carriers to be electrons in one wire and electrons or heavier holes in the other. Numerical results are presented for the intra- and inter-wire static structure factors, pair-correlation functions and the static charge density susceptibility over a wide range of system parameters (viz. temperature T, particle number density and inter-wire spacing) at equal and fixed transverse width of both the wires. We find for the first time that the coupled electron-hole (e-h) quantum wire system may favor a charge-density-wave (CDW) instability at sufficiently low T and carrier density in the close proximity of the wires, where as no such phase transition is observed in the electron-electron (e-e) quantum wire system at any non-zero T. The intra-wire contact pair-correlation functions of both the systems show a non-monotonous behavior with increasing (decreasing) T (carrier number density), and increase consistently with decrease in inter-wire spacing. On the other hand, the corresponding inter-wire contact pair-correlation functions show a non-monotonous T-dependence and consistent increase with decrease in carrier number density and/or inter-wire separation. Results of free exchange-correlation energy for both the e-h and e-e coupled systems are also reported which are found to have a noticeable dependence upon T. To highlight the effect of exchange-correlations, our results have been compared with the predictions of the random-phase approximation (RPA).