Dipolar superfluidity in electron-hole bilayer systems

TL;DR

This paper predicts a novel dipolar superfluid state in electron-hole bilayer systems, where excitonic condensation leads to unique supercurrents tunable by magnetic fields, highlighting the composite nature of excitons.

Contribution

It introduces the concept of dipolar superfluidity in electron-hole bilayers and describes how it differs from conventional superfluid states.

Findings

Existence of dipolar supercurrent tunable by in-plane magnetic field

Detection method via independent contacts to layers

Role of vortices in the superfluid properties

Abstract

Bilayer electron-hole systems, where the electrons and holes are created via doping and confined to separate layers, undergo excitonic condensation when the distance between the layers is smaller than typical distance between particles within a layer. We argue that the excitonic condensate is a novel dipolar superfluid in which the phase of the condensate couples to the {\it gradient} of the vector potential. We predict the existence of dipolar supercurrent which can be tuned by an in-plane magnetic field and detected by independent contacts to the layers. Thus the dipolar superfluid offers an example of excitonic condensate in which the {\it composite} nature of its constituent excitons is manifest in the macroscopic superfluid state. We also discuss various properties of this superfluid including the role of vortices.