Valley charge-transfer insulator in twisted double bilayer WSe2
Abstract In flat-band systems, emergent physics can be substantially modified by the presence of another nearby electronic band. For example, a Mott˘Hubbard insulator can turn into a charge transfer insulator if other electronic states enter between the upper and lower Hubbard bands. Here, we introd...
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| Language: | English |
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Nature Portfolio
2025-01-01
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| Series: | Nature Communications |
| Online Access: | https://doi.org/10.1038/s41467-025-56490-w |
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| author | LingNan Wei Qingxin Li Majeed Ur Rehman Yangchen He Dongdong An Shiwei Li Kenji Watanabe Takashi Taniguchi Martin Claassen Kostya S. Novoselov Dante M. Kennes Angel Rubio Daniel A. Rhodes Lede Xian Geliang Yu Lei Wang |
| author_facet | LingNan Wei Qingxin Li Majeed Ur Rehman Yangchen He Dongdong An Shiwei Li Kenji Watanabe Takashi Taniguchi Martin Claassen Kostya S. Novoselov Dante M. Kennes Angel Rubio Daniel A. Rhodes Lede Xian Geliang Yu Lei Wang |
| author_sort | LingNan Wei |
| collection | DOAJ |
| description | Abstract In flat-band systems, emergent physics can be substantially modified by the presence of another nearby electronic band. For example, a Mott˘Hubbard insulator can turn into a charge transfer insulator if other electronic states enter between the upper and lower Hubbard bands. Here, we introduce twisted double bilayer (TDB) WSe2, with twist angles near 60°, as a controllable platform in which the K-valley band can be tuned to close vicinity of the Γ-valley moiré flat band. At half-filling, correlations split the Γ-valley flat band into upper and lower Hubbard bands and a charge-transfer insulator forms between the Γ-valley upper Hubbard band and K-valley band. Using gate control, we continuously move the K-valley band across the Γ-valley Hubbard bands, and observe a tunable charge-transfer insulator gap and subsequently a continuous phase transition to a metal. The tuning of Mott˘Hubbard to charge-transfer insulator establishes valley degree of freedom as a suitable knob for transitions between exotic correlated phases. |
| format | Article |
| id | doaj-art-aceb6073d7b540629debe71d97272736 |
| institution | Kabale University |
| issn | 2041-1723 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Nature Communications |
| spelling | doaj-art-aceb6073d7b540629debe71d972727362025-02-02T12:31:41ZengNature PortfolioNature Communications2041-17232025-01-011611710.1038/s41467-025-56490-wValley charge-transfer insulator in twisted double bilayer WSe2LingNan Wei0Qingxin Li1Majeed Ur Rehman2Yangchen He3Dongdong An4Shiwei Li5Kenji Watanabe6Takashi Taniguchi7Martin Claassen8Kostya S. Novoselov9Dante M. Kennes10Angel Rubio11Daniel A. Rhodes12Lede Xian13Geliang Yu14Lei Wang15National Laboratory of Solid-State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing UniversityNational Laboratory of Solid-State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing UniversitySongshan Lake Materials LaboratoryDepartment of Materials Science and Engineering, University of WisconsinNational Laboratory of Solid-State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing UniversityNational Laboratory of Solid-State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing UniversityResearch Center for Electronic and Optical Materials, National Institute for Materials ScienceResearch Center for Materials Nanoarchitectonics, National Institute for Materials ScienceDepartment of Physics and Astronomy, University of PennsylvaniaDepartment of Materials Science and Engineering, National University of SingaporeInstitut für Theorie der Statistischen Physik, RWTH Aachen University and JARA-Fundamentals of Future Information TechnologyMax Planck Institute for the Structure and Dynamics of Matter, Center for Free-Electron Laser Science (CFEL)Department of Materials Science and Engineering, University of WisconsinSongshan Lake Materials LaboratoryNational Laboratory of Solid-State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing UniversityNational Laboratory of Solid-State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing UniversityAbstract In flat-band systems, emergent physics can be substantially modified by the presence of another nearby electronic band. For example, a Mott˘Hubbard insulator can turn into a charge transfer insulator if other electronic states enter between the upper and lower Hubbard bands. Here, we introduce twisted double bilayer (TDB) WSe2, with twist angles near 60°, as a controllable platform in which the K-valley band can be tuned to close vicinity of the Γ-valley moiré flat band. At half-filling, correlations split the Γ-valley flat band into upper and lower Hubbard bands and a charge-transfer insulator forms between the Γ-valley upper Hubbard band and K-valley band. Using gate control, we continuously move the K-valley band across the Γ-valley Hubbard bands, and observe a tunable charge-transfer insulator gap and subsequently a continuous phase transition to a metal. The tuning of Mott˘Hubbard to charge-transfer insulator establishes valley degree of freedom as a suitable knob for transitions between exotic correlated phases.https://doi.org/10.1038/s41467-025-56490-w |
| spellingShingle | LingNan Wei Qingxin Li Majeed Ur Rehman Yangchen He Dongdong An Shiwei Li Kenji Watanabe Takashi Taniguchi Martin Claassen Kostya S. Novoselov Dante M. Kennes Angel Rubio Daniel A. Rhodes Lede Xian Geliang Yu Lei Wang Valley charge-transfer insulator in twisted double bilayer WSe2 Nature Communications |
| title | Valley charge-transfer insulator in twisted double bilayer WSe2 |
| title_full | Valley charge-transfer insulator in twisted double bilayer WSe2 |
| title_fullStr | Valley charge-transfer insulator in twisted double bilayer WSe2 |
| title_full_unstemmed | Valley charge-transfer insulator in twisted double bilayer WSe2 |
| title_short | Valley charge-transfer insulator in twisted double bilayer WSe2 |
| title_sort | valley charge transfer insulator in twisted double bilayer wse2 |
| url | https://doi.org/10.1038/s41467-025-56490-w |
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