On some structural phase transitions in coupled quantum wires at finite temperature

Abstract

Abstract In this paper, we explore some structural phase transitions in GaAs-based coupled electron-electron (e-e) and electron-hole (e-h) quantum wires at finite temperature. To this endeavour, the intra- and inter-wire static-structure factors, pair-correlation functions and static (charge) density susceptibilities are calculated over a wide range of temperature T, particle number density parameter r se and some selected values of inter-wire spacing d. The particle exchange-correlations (xc) are included using the dynamic version of self-consistent mean-field theory of Singwi et al (the qSTLS theory), and the results have been compared with the static STLS model. It has been found that in the e-h system, the inclusion of dynamic nature of xc leads to the formation of Wigner crystal (WC) state in the close proximity of two wires at wave-vector q ∼ 3.5k Fe . However, a charge-density-wave (CDW) instability is observed at q ∼ 2k Fe when the xc are treated statically (k Fe being the electron’s Fermi wave vector). On the other hand, the e-e system shows comparatively small signatures of the WC phase when wires are kept sufficiently far apart, but, a long-wavelength instability is encountered in close vicinity of the wires. Interestingly, the CDW phase is completely missing in the e-e system at the investigated parameters. Expectedly, the quantum phase transitions are predicted to occur in the strongly correlated regime i.e. at sufficiently small T and high r se .