Short note on the excitonic Mott phase

TL;DR

This paper analyzes an exciton gas on a lattice using a hopping expansion, establishing conditions for a Mott phase characterized by exponential decay of correlations due to strong fluctuations, regardless of temperature.

Contribution

It provides a sufficient condition for the exciton hopping rate to induce a Mott phase with short-range correlations, highlighting the role of fluctuations.

Findings

Existence of a Mott phase with exponential decay of correlations

Conditions for hopping rate to induce the Mott phase

Fluctuations destroy long-range order at any temperature

Abstract

An exciton gas on a lattice is analyzed in terms of a convergent hopping expansion. For a given chemical potential our calculation provides a sufficient condition for the hopping rate to obtain an exponential decay of the exciton correlation function. This result indicates the existence of a Mott phase in which strong fluctuations destroy the long range correlations in the exciton gas at any temperature, either by thermal or by quantum fluctuations.