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

Journal Article · Mon Aug 25 00:00:00 EDT 2025 · Nature Materials

DOI:https://doi.org/10.1038/s41563-025-02316-5· OSTI ID:3008743

Qi, Ruishi; Li, Qize; Zhang, Zuocheng; Nie, Jiahui; Zou, Bo; Cui, Zhiyuan; Kim, Haleem; Sanborn, Collin; Chen, Sudi; Xie, Jingxu; Taniguchi, Takashi; Watanabe, Kenji; Crommie, Michael F; MacDonald, Allan H; Wang, Feng

Excitonic insulators represent a unique quantum phase of matter that enables the study of 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. On the basis of electron–hole bilayers made of MoSe2/hexagonal boron nitride/WSe2 heterostructures, here we study the behaviour 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, and enable further exploration of quantum phenomena in composite bosonic insulators.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: US Department of Energy; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Materials Sciences & Engineering Division (SC-22.2)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 3008743
• Journal Information: Nature Materials, Journal Name: Nature Materials Journal Issue: 1 Vol. 25
• Country of Publication: United States
• Language: English