Bilayer WSe as a natural platform for interlayer exciton condensates in the strong coupling limit.
Qianhui Shi, En-Min Shih, Daniel Rhodes, Bumho Kim, Katayun Barmak, Kenji Watanabe, Takashi Taniguchi, Zlatko Papić, Dmitry A Abanin, James Hone, Cory R Dean
Author Information
Qianhui Shi: Department of Physics, Columbia University, New York, NY, USA. ORCID
En-Min Shih: Department of Physics, Columbia University, New York, NY, USA. ORCID
Daniel Rhodes: Department of Mechanical Engineering, Columbia University, New York, NY, USA.
Bumho Kim: Department of Mechanical Engineering, Columbia University, New York, NY, USA. ORCID
Katayun Barmak: Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, USA. ORCID
Kenji Watanabe: Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan. ORCID
Takashi Taniguchi: International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan. ORCID
Zlatko Papić: School of Physics and Astronomy, University of Leeds, Leeds, UK.
Dmitry A Abanin: Department of Theoretical Physics, University of Geneva, Geneva, Switzerland.
James Hone: Department of Mechanical Engineering, Columbia University, New York, NY, USA. ORCID
Cory R Dean: Department of Physics, Columbia University, New York, NY, USA. cd2478@columbia.edu.
Exciton condensates (ECs) are macroscopic coherent states arising from condensation of electron-hole pairs. Bilayer heterostructures, consisting of two-dimensional electron and hole layers separated by a tunnel barrier, provide a versatile platform to realize and study ECs. The tunnel barrier suppresses recombination, yielding long-lived excitons. However, this separation also reduces interlayer Coulomb interactions, limiting the exciton binding strength. Here, we report the observation of ECs in naturally occurring 2H-stacked bilayer WSe. In this system, the intrinsic spin-valley structure suppresses interlayer tunnelling even when the separation is reduced to the atomic limit, providing access to a previously unattainable regime of strong interlayer coupling. Using capacitance spectroscopy, we investigate magneto-ECs, formed when partially filled Landau levels couple between the layers. We find that the strong-coupling ECs show dramatically different behaviour compared with previous reports, including an unanticipated variation of EC robustness with the orbital number, and find evidence for a transition between two types of low-energy charged excitations. Our results provide a demonstration of tuning EC properties by varying the constituent single-particle wavefunctions.
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Grants
DE-SC0016703/DOE | SC | Basic Energy Sciences (BES)
