Experimental conditions for observation of electron-hole superfluidity in GaAs heterostructures

TL;DR

This paper identifies the specific experimental conditions under which electron-hole superfluidity can be observed in GaAs heterostructures, highlighting the potential for detecting superfluid pockets via quantum capacitance.

Contribution

It provides a detailed analysis of the parameter ranges for superfluidity in GaAs double quantum wells, incorporating self-consistent screening effects and exploring detection methods.

Findings

Superfluidity occurs within certain density and temperature ranges matching optical experiment indications.

Existing drag experiments are outside the superfluid regime.

Quantum capacitance can detect localized superfluid pockets in low-mobility samples.

Abstract

The experimental parameter ranges needed to generate superfluidity in optical and drag experiments in GaAs double quantum wells are determined, using a formalism that includes self-consistent screening of the Coulomb pairing interaction in the presence of the superfluid. The very different electron and hole masses in GaAs make this a particularly interesting system for superfluidity, with exotic superfluid phases predicted in the BCS-BEC crossover regime. We find that the density and temperature ranges for superfluidity cover the range for which optical experiments have observed indications of superfluidity, but that existing drag experiments lie outside the superfluid range. However we also show that for samples with low mobility with no macroscopically connected superfluidity, if the superfluidity survived in randomly distributed localized pockets, standard quantum capacitance measurements could detect these pockets.