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Strongly correlated excitonic insulator in atomic double layers

Author

Listed:
  • Liguo Ma

    (Cornell University)

  • Phuong X. Nguyen

    (Cornell University)

  • Zefang Wang

    (Cornell University)

  • Yongxin Zeng

    (University of Texas at Austin)

  • Kenji Watanabe

    (National Institute for Materials Science)

  • Takashi Taniguchi

    (National Institute for Materials Science)

  • Allan H. MacDonald

    (University of Texas at Austin)

  • Kin Fai Mak

    (Cornell University
    Cornell University
    Kavli Institute at Cornell for Nanoscale Science)

  • Jie Shan

    (Cornell University
    Cornell University
    Kavli Institute at Cornell for Nanoscale Science)

Abstract

Excitonic insulators (EIs) arise from the formation of bound electron–hole pairs (excitons)1,2 in semiconductors and provide a solid-state platform for quantum many-boson physics3–8. Strong exciton–exciton repulsion is expected to stabilize condensed superfluid and crystalline phases by suppressing both density and phase fluctuations8–11. Although spectroscopic signatures of EIs have been reported6,12–14, conclusive evidence for strongly correlated EI states has remained elusive. Here we demonstrate a strongly correlated two-dimensional (2D) EI ground state formed in transition metal dichalcogenide (TMD) semiconductor double layers. A quasi-equilibrium spatially indirect exciton fluid is created when the bias voltage applied between the two electrically isolated TMD layers is tuned to a range that populates bound electron–hole pairs, but not free electrons or holes15–17. Capacitance measurements show that the fluid is exciton-compressible but charge-incompressible—direct thermodynamic evidence of the EI. The fluid is also strongly correlated with a dimensionless exciton coupling constant exceeding 10. We construct an exciton phase diagram that reveals both the Mott transition and interaction-stabilized quasi-condensation. Our experiment paves the path for realizing exotic quantum phases of excitons8, as well as multi-terminal exciton circuitry for applications18–20.

Suggested Citation

  • Liguo Ma & Phuong X. Nguyen & Zefang Wang & Yongxin Zeng & Kenji Watanabe & Takashi Taniguchi & Allan H. MacDonald & Kin Fai Mak & Jie Shan, 2021. "Strongly correlated excitonic insulator in atomic double layers," Nature, Nature, vol. 598(7882), pages 585-589, October.
  • Handle: RePEc:nat:nature:v:598:y:2021:i:7882:d:10.1038_s41586-021-03947-9
    DOI: 10.1038/s41586-021-03947-9
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    Citations

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    Cited by:

    1. Ruishi Qi & Andrew Y. Joe & Zuocheng Zhang & Yongxin Zeng & Tiancheng Zheng & Qixin Feng & Jingxu Xie & Emma Regan & Zheyu Lu & Takashi Taniguchi & Kenji Watanabe & Sefaattin Tongay & Michael F. Cromm, 2023. "Thermodynamic behavior of correlated electron-hole fluids in van der Waals heterostructures," Nature Communications, Nature, vol. 14(1), pages 1-9, December.
    2. Qiang Gao & Yang-hao Chan & Yuzhe Wang & Haotian Zhang & Pu Jinxu & Shengtao Cui & Yichen Yang & Zhengtai Liu & Dawei Shen & Zhe Sun & Juan Jiang & Tai C. Chiang & Peng Chen, 2023. "Evidence of high-temperature exciton condensation in a two-dimensional semimetal," Nature Communications, Nature, vol. 14(1), pages 1-7, December.
    3. Benjamin I. Weintrub & Yu-Ling Hsieh & Sviatoslav Kovalchuk & Jan N. Kirchhof & Kyrylo Greben & Kirill I. Bolotin, 2022. "Generating intense electric fields in 2D materials by dual ionic gating," Nature Communications, Nature, vol. 13(1), pages 1-6, December.
    4. Binjie Zheng & Junzhuan Wang & Qianghua Wang & Xin Su & Tianye Huang & Songlin Li & Fengqiu Wang & Yi Shi & Xiaomu Wang, 2022. "Quantum criticality of excitonic Mott metal-insulator transitions in black phosphorus," Nature Communications, Nature, vol. 13(1), pages 1-7, December.
    5. Meng Zhao & Zhongjie Wang & Lu Liu & Chunzheng Wang & Cheng-Yen Liu & Fang Yang & Hua Wu & Chunlei Gao, 2024. "Atomic-scale visualization of the interlayer Rydberg exciton complex in moiré heterostructures," Nature Communications, Nature, vol. 15(1), pages 1-10, December.
    6. Andrew Y. Joe & Andrés M. Mier Valdivia & Luis A. Jauregui & Kateryna Pistunova & Dapeng Ding & You Zhou & Giovanni Scuri & Kristiaan De Greve & Andrey Sushko & Bumho Kim & Takashi Taniguchi & Kenji W, 2024. "Controlled interlayer exciton ionization in an electrostatic trap in atomically thin heterostructures," Nature Communications, Nature, vol. 15(1), pages 1-8, December.
    7. Cong Liu & Ion Errea & Chi Ding & Chris Pickard & Lewis J. Conway & Bartomeu Monserrat & Yue-Wen Fang & Qing Lu & Jian Sun & Jordi Boronat & Claudio Cazorla, 2023. "Excitonic insulator to superconductor phase transition in ultra-compressed helium," Nature Communications, Nature, vol. 14(1), pages 1-9, December.
    8. Yanhao Tang & Jie Gu & Song Liu & Kenji Watanabe & Takashi Taniguchi & James C. Hone & Kin Fai Mak & Jie Shan, 2022. "Dielectric catastrophe at the Wigner-Mott transition in a moiré superlattice," Nature Communications, Nature, vol. 13(1), pages 1-7, December.

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