中国物理B ›› 2026, Vol. 35 ›› Issue (2): 27202-027202.doi: 10.1088/1674-1056/ae2116

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Electronic correlations and topological states at the interface of twisted bilayer graphene and chromium oxychloride

Minsheng Li(李旻晟)1, Zehao Jia(贾泽浩)1, Xiangyu Cao(曹翔宇)1, Qiang Ma(马强)1, Chang Jiang(蒋昶)1, Yuda Zhang(张钰达)1, Linfeng Ai(艾临风)1, Pengliang Leng(冷鹏亮)1, and Faxian Xiu(修发贤)1,2,3,4,†   

  1. 1 State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China;
    2 Shanghai Research Center for Quantum Sciences, Shanghai 201315, China;
    3 Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China;
    4 Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 201210, China
  • 收稿日期:2025-10-09 修回日期:2025-11-14 接受日期:2025-11-19 发布日期:2026-01-31
  • 通讯作者: Faxian Xiu E-mail:Faxian@fudan.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 52225207 and 52350001), the Shanghai Pilot Program for Basic Research–Fudan University 21TQ1400100 (Grant No. 21TQ006), and the Shanghai Municipal Science and Technology Major Project (Grant No. 2019SHZDZX01).

Electronic correlations and topological states at the interface of twisted bilayer graphene and chromium oxychloride

Minsheng Li(李旻晟)1, Zehao Jia(贾泽浩)1, Xiangyu Cao(曹翔宇)1, Qiang Ma(马强)1, Chang Jiang(蒋昶)1, Yuda Zhang(张钰达)1, Linfeng Ai(艾临风)1, Pengliang Leng(冷鹏亮)1, and Faxian Xiu(修发贤)1,2,3,4,†   

  1. 1 State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China;
    2 Shanghai Research Center for Quantum Sciences, Shanghai 201315, China;
    3 Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China;
    4 Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 201210, China
  • Received:2025-10-09 Revised:2025-11-14 Accepted:2025-11-19 Published:2026-01-31
  • Contact: Faxian Xiu E-mail:Faxian@fudan.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 52225207 and 52350001), the Shanghai Pilot Program for Basic Research–Fudan University 21TQ1400100 (Grant No. 21TQ006), and the Shanghai Municipal Science and Technology Major Project (Grant No. 2019SHZDZX01).

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摘要： When two layers of graphene are stacked with a twist angle of approximately 1.1°, strong interlayer coupling gives rise to a pair of flat bands in twisted bilayer graphene (TBG), resulting in pronounced electron-electron interactions. At half filling of the flat bands, TBG exhibits correlated insulating states. Here, we investigate the electrical transport properties of heterostructures composed of TBG and the antiferromagnetic insulator chromium oxychloride (CrOCl), and propose a strategy to modulate the correlated insulating states in TBG. During the transition from a conventional phase to a strong interfacial coupling phase, kink-like features are observed in the charge neutrality point (CNP), correlated insulating state, and band insulating state. Under a perpendicular magnetic field, the system exhibits broadened quantum Hall plateaus in the strong interfacial coupling regime. Electrons localized in the CrOCl layer screen the bottom gate, rendering the carrier density in TBG less sensitive to variations in the bottom gate voltage. These phenomena are well captured by a charge-transfer model between TBG and CrOCl. Our results provide insights into the control of electronic correlations and topological states in graphene moiré systems via interfacial charge coupling.

关键词: twisted bilayer graphene, correlated insulating state, CrOCl, interfacial coupling, charge transfer

Abstract: When two layers of graphene are stacked with a twist angle of approximately 1.1°, strong interlayer coupling gives rise to a pair of flat bands in twisted bilayer graphene (TBG), resulting in pronounced electron-electron interactions. At half filling of the flat bands, TBG exhibits correlated insulating states. Here, we investigate the electrical transport properties of heterostructures composed of TBG and the antiferromagnetic insulator chromium oxychloride (CrOCl), and propose a strategy to modulate the correlated insulating states in TBG. During the transition from a conventional phase to a strong interfacial coupling phase, kink-like features are observed in the charge neutrality point (CNP), correlated insulating state, and band insulating state. Under a perpendicular magnetic field, the system exhibits broadened quantum Hall plateaus in the strong interfacial coupling regime. Electrons localized in the CrOCl layer screen the bottom gate, rendering the carrier density in TBG less sensitive to variations in the bottom gate voltage. These phenomena are well captured by a charge-transfer model between TBG and CrOCl. Our results provide insights into the control of electronic correlations and topological states in graphene moiré systems via interfacial charge coupling.

Key words: twisted bilayer graphene, correlated insulating state, CrOCl, interfacial coupling, charge transfer

中图分类号:  (Electronic transport in graphene)

  • 72.80.Vp
73.63.-b (Electronic transport in nanoscale materials and structures)