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The metal-insulator transition (MIT) driven by electronic correlations is a fundamental and challenging problem in condensed-matter physics. Particularly, whether such a transition can be continuous remains open. The emergence of semiconducting moiré materials with continuously tunable bandwidth provides an ideal platform to study interaction-driven MITs. Although a bandwidth-tuned MIT at fixed full electron filling of the moiré superlattice has been reported recently, that at fractional filling, which involves translational symmetry breaking of the underlying superlattice, remains elusive. Here, we demonstrate bandwidth-tuned MITs in a MoSe2/WS2 moiré superlattice at both integer and fractional fillings using the exciton sensing technique. The bandwidth is controlled by an out-of-plane electric field. The dielectric response is probed optically with the 2s exciton in a remote WSe2 sensor layer. The exciton spectral weight is negligible for the metallic state, consistent with a large negative dielectric constant. It continuously vanishes when the transition is approached from the insulating side, corresponding to a diverging dielectric constant or a ‘dielectric catastrophe’. Our results support continuous interaction-driven MITs in a two-dimensional triangular lattice and stimulate future explorations of exotic quantum phases, such as quantum spin liquids, in their vicinities.

権利情報:

• Creative Commons BY Attribution 4.0 International
  

キーワード: Wigner-Mott transition, MoSe2/WS2, dielectric catastrophe

刊行年月日: 2022-07-25

出版者: Springer Science and Business Media LLC

掲載誌:

• Nature Communications (ISSN: 20411723) vol. 13 issue. 1 4271

研究助成金:

原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.1038/s41467-022-32037-1

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更新時刻: 2025-02-27 16:31:00 +0900

MDRでの公開時刻: 2025-02-27 16:31:00 +0900