Superfluidity of dipole excitons in two layers of gapped graphene

TL;DR

This paper investigates the superfluidity of dipole excitons in gapped double-layer graphene, analyzing how energy gaps and interlayer separation influence superfluid properties and phase transition temperatures.

Contribution

It models exciton formation and superfluidity in gapped double-layer graphene, proposing controllable superfluid behavior via energy gaps and layer separation.

Findings

Superfluid density decreases with increasing energy gaps and interlayer separation.

The Kosterlitz-Thouless transition temperature is tunable by these parameters.

Energy spectrum and exciton mass depend on gaps and separation.

Abstract

A study of the formation of excitons as a problem of two Dirac particles confined in two-layer graphene sheets separated by a dielectric when gaps are opened and they interact via a Coulomb potential is presented. We propose to observe Bose-Einstein condensation and superfluidity of quasi-two-dimensional dipole excitons in double layer graphene in the presence of band gaps. The energy spectrum of the collective excitations, the sound spectrum, and the effective exciton mass are functions of the energy gaps, density and interlayer separation. The superfluid density ns and temperature of the Kosterlitz-Thouless phase transition Tc are decreasing functions of the energy gaps as well as the interlayer separation, and therefore, could be controlled by these parameters.