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Twisting and stacking atomically-thin materials provides a versatile platform for investigating emergent quantum phases of matter driven by strong correlation and non-trivial topology. Novel phenomena such as correlated insulating states, unconventional superconductivity, and the quantum anomalous Hall effect have been observed in several twisted moiré systems, but fully understanding the underlying microscopic mechanisms remains challenging. Measurements performed on different samples of the same twisted system often exhibit different low-temperature phase diagrams, suggesting that the ground states of these materials could be susceptible to local structural inhomogeneity that is difficult to capture through macroscopic probes. We have used scanning tunneling microscopy and spectroscopy to demonstrate the interplay between correlation, topology, and local structural parameters in determining the behavior of twisted monolayer-bilayer graphene. We observe local spectroscopic signatures for correlated insulating states having total Chern number Ctot = ±2 at ¾-filling of the conduction moiré mini-band and have characterized their evolution in an out-of-plane magnetic field. We have determined the relationship between topological behavior and local twist angle accompanied by hetero-strain, and show that the sign of Ctot can be controlled via electrostatic gating over a limited range of twist angles under small strain but not as the strain grows larger. The electrical control of Chern number results from a competition between the orbital magnetizations of filled bulk bands and chiral edge states that is sensitive to strain-induced distortion in the moiré superlattice.

権利情報:

• Creative Commons BY Attribution 4.0 International
  

キーワード: Correlated insulating states, unconventional superconductivity, moiré heterostructures2¥

刊行年月日: 2023-06-16

出版者: Springer Science and Business Media LLC

掲載誌:

• Nature Communications (ISSN: 20411723) vol. 14 issue. 1 3595

研究助成金:

• DOE | SC | Basic Energy Sciences Center for Novel Pathways to Quantum Coherence in Materials, an Energy Frontier Research Center
• DOE | SC | Basic Energy Sciences KCWF16
• DOE | SC | Basic Energy Sciences Molecular Foundry at LBNL
• DOE | SC | Basic Energy Sciences KCWF16
• DOE | SC | Basic Energy Sciences Center for Novel Pathways to Quantum Coherence in Materials, an Energy Frontier Research Center
• DOE | SC | Basic Energy Sciences KC2301
• DOE | SC | Basic Energy Sciences KCWF16
• DOE | SC | Basic Energy Sciences Molecular Foundry at LBNL
• DOE | SC | Basic Energy Sciences Center for Novel Pathways to Quantum Coherence in Materials, an Energy Frontier Research Center
• DOE | SC | Basic Energy Sciences KCWF16
• DOE | SC | Basic Energy Sciences Molecular Foundry at LBNL
• DOE | SC | Basic Energy Sciences Center for Novel Pathways to Quantum Coherence in Materials, an Energy Frontier Research Center
• DOE | SC | Basic Energy Sciences KCWF16
• DOE | SC | Basic Energy Sciences Molecular Foundry at LBNL
• DOE | SC | Basic Energy Sciences KC2301
• National Science Foundation DMR-2221750
• National Science Foundation DMR-2221750
• National Science Foundation DMR-2221750
• National Science Foundation DMR-2221750
• C.Z. acknowledges support from a Kavli ENSI Philomathia Graduate Student Fellowship.
• T.S. acknowledges fellowship support from the Masason Foundation.
• MEXT | Japan Society for the Promotion of Science 20H00354, 21H05233, 23H02052
• MEXT | Japan Society for the Promotion of Science 20H00354, 21H05233, 23H02052
• Ministry of Education, Culture, Sports, Science and Technology World Premier International Research Center Initiative (WPI)
• Ministry of Education, Culture, Sports, Science and Technology World Premier International Research Center Initiative (WPI)

原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.1038/s41467-023-39110-3

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更新時刻: 2025-02-15 12:31:37 +0900

MDRでの公開時刻: 2025-02-15 12:31:37 +0900