Exciton Condensate Modulation in Electron-Hole Bilayers: A Real-Space Visualization

TL;DR

This paper investigates how exciton condensates in electron-hole bilayers change with density polarization, revealing phase transitions and modulated states, and visualizes these phenomena through real-space modeling.

Contribution

It introduces a real-space mean-field model to visualize exciton condensate textures and identifies phase transitions and modulated states with varying density polarization.

Findings

Phase transitions from superfluid to normal state with increased polarization

Identification of stripe-like and modulated exciton states

Observation of intra-gap resonance quasiparticle states

Abstract

We study the texture of the exciton condensate at low temperatures in an independently gated electron-hole bilayer system. A model Hamiltonian is solved in real space within a mean-field approximation. It is found that, with increased electron-hole density polarization, the system experiences phase transformations from the zero center-of-mass momentum superfluid state, through one- and two-dimensional exciton pair modulated states, into the normal state. At weak density polarization, the modulating state resembles the Larkin-Ovchinikov state in superconductors in the presence of an exchange field in the weak-coupling BCS limit, and becomes stripe-like in the strong coupling BEC limit. In the one-dimensional modulated phase, the density of states exhibits low-energy intra-gap resonance quasiparticle states, which are localized in the nodal region.