Quantum Phase Transition of the Electron-Hole Liquid In the Coupled Quantum Wells

TL;DR

This paper investigates the quantum phase transition in coupled quantum wells, revealing conditions for plasma instability, phase separation, and the emergence of charge density waves, with significant mass and Z-factor renormalizations.

Contribution

It provides a theoretical analysis of the instability and phase transition mechanisms in electron-hole liquids within coupled quantum wells, highlighting the role of well separation and plasmon spectrum.

Findings

Homogeneous plasma becomes unstable at low densities.

Phase separation into gas and electron-hole liquid occurs.

Charge density waves emerge at critical well separation.

Abstract

Many-component electron-hole plasma is considered in the Coupled Quantum Wells (CQW). It is found that the homogeneous state of the plasma is unstable if the carrier density is sufficiently small. The instability results in the breakdown into two coexisting phase - a low-density gas phase and a high-density electron-hole liquid. The homogeneous state of the electron-hole liquid is stable if the distance between the quantum wells l is sufficiently small. However, as the distance l increases and reaches a certain critical value, the plasmon spectrum of the electron-hole liquid becomes unstable. Hereupon, a quantum phase transition occurs, resulting in the appearance of the charge density waves of finite amplitude in both quantum wells. The strong mass renormalization and the strong Z-factor renormalization are found for the electron-hole liquid as the quantum phase transition occurs.