Perfect Coulomb drag and exciton transport in an excitonic insulator
Strongly coupled electron-hole bilayers can host quantum states of interlayer excitons, such as high-temperature exciton condensates at zero magnetic field. This state is predicted to feature perfect Coulomb drag, where a current in one layer is accompanied by an equal but opposite current in the other. We used an optical technique to probe the electrical transport of correlated electron-hole bilayers based on MoSe<sub>2</sub>/hBN/WSe<sub>2</sub> heterostructures. We observed perfect Coulomb drag in the excitonic insulator phase at low temperatures; the counterflow resistance of interlayer excitons remained finite. These results indicate the formation of an exciton gas that does not condense into a superfluid. Our work demonstrates that dynamic optical spectroscopy provides a powerful tool for probing exciton transport behavior in correlated electron-hole fluids.
Authors
- Sefaattin Tongay (ORCID: https://orcid.org/0000-0001-8294-984X)
- Ruishi Qi (ORCID: https://orcid.org/0009-0000-1305-1104)
- Takashi Taniguchi (ORCID: https://orcid.org/0000-0002-1467-3105)
- Kenji Watanabe (ORCID: https://orcid.org/0000-0003-3701-8119)
- Jingxu Xie (ORCID: https://orcid.org/0009-0000-9691-2474)
- Andrew Y. Joe (ORCID: https://orcid.org/0000-0003-4376-7386)
- Qixin Feng (ORCID: https://orcid.org/0000-0003-1756-0090)
- Feng Wang (ORCID: https://orcid.org/0000-0001-8369-6194)
- Ziyu Wang (ORCID: https://orcid.org/0009-0000-4641-5082)
- Zuocheng Zhang (ORCID: https://orcid.org/0000-0001-7851-6101)
- Zheyu Lu
Institutions
- University of California, Riverside (US)
- Lawrence Berkeley National Laboratory (US)
- National Institute for Materials Science (JP)
- Kavli Energy NanoScience Institute (US)
- Arizona State University (US)
- Xi'an Jiaotong University (CN)
- University of California, Berkeley (US)
Publication Details
- Journal
- Science
- Published
- 2025-04-17
- DOI
- https://doi.org/10.1126/science.adl1839
- Citations
- 22
- Primary Topic
- Perovskite Materials and Applications
- Type
- article
- Field-Weighted Citation Impact
- 16.07