Electron-hole pairing in topological insulator thin film

TL;DR

This paper investigates the conditions under which electron-hole pairing occurs in topological insulator thin films, predicting a topological exciton condensate with potential observable signatures and discussing experimental parameters.

Contribution

It provides a quantitative analysis of the critical temperature for electron-hole pairing, considering screening, disorder, and hybridization effects in topological insulator thin films.

Findings

Predicted observable increase in the energy gap below the hybridization value.

Quantitative estimates of critical temperature for pairing.

Discussion of experimental parameters necessary for observation.

Abstract

We consider pairing of massless Dirac electrons and holes located on opposite surfaces of thin film of "strong" three-dimensional topological insulator. Such pairing was predicted to give rise to topological exciton condensate with unusual properties. We estimate quantitatively achievable critical temperature of the pairing with taking into account self-consistent screening of the Coulomb interaction, disorder and hybridization of electron and hole states caused by a tunneling through the film. Increase of the gap above the hybridization value when the temperature is lowered can be observable signature of the pairing. System parameters required to observe the electron-hole pairing are discussed.