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

doi:10.1088/1674-1056/ae2116

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.

Keywords: twisted bilayer graphene correlated insulating state CrOCl interfacial coupling charge transfer

Received: 09 October 2025
Revised: 14 November 2025
Accepted manuscript online: 19 November 2025

PACS:	72.80.Vp	(Electronic transport in graphene)
	73.63.-b	(Electronic transport in nanoscale materials and structures)
	73.43.-f	(Quantum Hall effects)

Fund: 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).

Corresponding Authors: Faxian Xiu
E-mail: Faxian@fudan.edu.cn

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Minsheng Li(李旻晟), Zehao Jia(贾泽浩), Xiangyu Cao(曹翔宇), Qiang Ma(马强), Chang Jiang(蒋昶), Yuda Zhang(张钰达), Linfeng Ai(艾临风), Pengliang Leng(冷鹏亮), and Faxian Xiu(修发贤) Electronic correlations and topological states at the interface of twisted bilayer graphene and chromium oxychloride 2026 Chin. Phys. B 35 027202

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

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