Exciton-Mott Physics in Two-Dimensional Electron-Hole Systems: Phase Diagram and Single-Particle Spectra

TL;DR

This paper investigates the phase transitions between exciton gas and electron-hole plasma in 2D systems, revealing detailed crossover behaviors, phase diagram features, and spectral signatures of excitonic correlations.

Contribution

Develops a self-consistent screened T-matrix approach to map the global phase diagram and analyze exciton-Mott crossover in 2D electron-hole systems.

Findings

Identifies a pure Mott transition point with discontinuous ionization ratio.

Provides a detailed phase diagram beyond the traditional Mott density concept.

Reveals spectral features reflecting excitonic correlations.

Abstract

Exciton Mott physics in two-dimensional electron-hole (e-h) systems is studied in the quasiequilibrium, which is the crossovers or phase transitions between the insulating exciton gas and the metallic e-h plasma. By developing a self-consistent screened T-matrix approximation, we succeed in obtaining the "global" phase diagram on the plane of the e-h density and the temperature as a contour plot of the exciton ionization ratio. The detailed features of the exciton-Mott crossover at high temperature are figured out beyond the conventionally used concept of the Mott density. At low temperature, we find not only the region unstable toward the inhomogeneity but the pure Mott transition point characterized by the discontinuity in the ionization ratio. The single particle spectra also exhibit interesting features reflecting the excitonic correlations.