Dynamic correlations in symmetric electron-electron and electron-hole bilayers

TL;DR

This paper investigates the ground-state properties of symmetric electron-electron and electron-hole bilayers using the quantum STLS theory, revealing phase transitions and comparing results with diffusion Monte Carlo simulations.

Contribution

It introduces the application of qSTLS theory to bilayers, showing improved agreement with DMC and identifying phase transitions to Wigner crystal states.

Findings

qSTLS results differ from conventional STLS and align better with DMC.

Phase transition from liquid to Wigner crystal occurs at low density and small layer separation.

qSTLS predicts a phase transition consistent with DMC findings.

Abstract

The ground-state behavior of the symmetric electron-electron and electron-hole bilayers is studied by including dynamic correlation effects within the quantum version of Singwi, Tosi, Land, and Sjolander (qSTLS) theory. The static pair-correlation functions, the local-field correction factors, and the ground-state energy are calculated over a wide range of carrier density and layer spacing. The possibility of a phase transition into a density-modulated ground state is also investigated. Results for both the electron-electron and electron-hole bilayers are compared with those of recent diffusion Monte Carlo (DMC) simulation studies. We find that the qSTLS results differ markedly from those of the conventional STLS approach and compare in the overall more favorably with the DMC predictions. An important result is that the qSTLS theory signals a phase transition from the liquid to the coupled Wigner crystal ground state, in both the electron-electron and electron-hole bilayers, below a critical density and in the close proximity of layers (d <~ r_sa_0^*), in qualitative agreement with the findings of the DMC simulations.