Competition between excitonic insulators and quantum Hall states in correlated electron-hole bilayers

TL;DR

This paper investigates the competition between excitonic insulator phases and quantum Hall states in electron-hole bilayers, revealing quantum phase transitions driven by magnetic fields in MoSe2/hBN/WSe2 heterostructures.

Contribution

It provides experimental evidence of quantum oscillations and phase transitions between excitonic insulators and quantum Hall states in correlated electron-hole bilayers.

Findings

Observation of excitonic quantum oscillations in Coulomb drag and resistance.

Identification of multiple quantum phase transitions under strong magnetic fields.

Demonstration of interplay between electron-hole interactions and Landau level quantization.

Abstract

Excitonic insulators represent a unique quantum phase of matter, providing a rich ground for studying exotic quantum bosonic states. Strongly coupled electron-hole bilayers, which host stable dipolar exciton fluids with an exciton density that can be adjusted electrostatically, offer an ideal platform to investigate correlated excitonic insulators. Based on electron-hole bilayers made of MoSe2/hBN/WSe2 heterostructures, here we study the behavior of excitonic insulators in a perpendicular magnetic field. We report the observation of excitonic quantum oscillations in both Coulomb drag signals and electrical resistance at low to medium magnetic fields. Under a strong magnetic field, we identify multiple quantum phase transitions between the excitonic insulator phase and the bilayer quantum Hall insulator phase. These findings underscore the interplay between the electron-hole interactions and Landau level quantization that opens new possibilities for exploring quantum phenomena in composite bosonic insulators.