Unconventional correlated insulator in CrOCl-interfaced Bernal bilayer graphene

Kaining Yang; Xiang Gao; Yaning Wang; Tongyao Zhang; Yuchen Gao; Xin Lu; Shihao Zhang; Jianpeng Liu; Pingfan Gu; Zhaoping Luo; Runjie Zheng; Shimin Cao; Hanwen Wang; Xingdan Sun; Kenji Watanabe; Takashi Taniguchi; Xiuyan Li; Jing Zhang; Xi Dai; Jian-Hao Chen; Yu Ye; Zheng Han

doi:10.1038/s41467-023-37769-2

Unconventional correlated insulator in CrOCl-interfaced Bernal bilayer graphene

Nat Commun. 2023 Apr 14;14(1):2136. doi: 10.1038/s41467-023-37769-2.

Authors

Kaining Yang^#^{1

2}, Xiang Gao^#^{1

2}, Yaning Wang^#^{3

4}, Tongyao Zhang^#^{1

2}, Yuchen Gao^{5

6}, Xin Lu⁷, Shihao Zhang⁸, Jianpeng Liu^{8

9}, Pingfan Gu^{5

6}, Zhaoping Luo³, Runjie Zheng¹⁰, Shimin Cao^{10

11}, Hanwen Wang³, Xingdan Sun³, Kenji Watanabe¹², Takashi Taniguchi¹³, Xiuyan Li³, Jing Zhang^{1

2}, Xi Dai^{14

15}, Jian-Hao Chen^{16

17

18

19}, Yu Ye^{20

21}, Zheng Han^{22

23

24}

Affiliations

¹ State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, PR China.
² Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, PR China.
³ Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China.
⁴ School of Material Science and Engineering, University of Science and Technology of China, Anhui, China.
⁵ Collaborative Innovation Center of Quantum Matter, Beijing, China.
⁶ State Key Lab for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing, China.
⁷ School of Physical Science and Technology, ShanghaiTech University, Shanghai, China. lvxin@shanghaitech.edu.cn.
⁸ School of Physical Science and Technology, ShanghaiTech University, Shanghai, China.
⁹ ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai, China.
¹⁰ International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.
¹¹ Beijing Academy of Quantum Information Sciences, Beijing, China.
¹² Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan.
¹³ International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan.
¹⁴ Materials Department, University of California, Santa Barbara, CA, USA. daix@ust.hk.
¹⁵ Department of Physics, The Hongkong University of Science and Technology, Hong Kong, China. daix@ust.hk.
¹⁶ International Center for Quantum Materials, School of Physics, Peking University, Beijing, China. chenjianhao@pku.edu.cn.
¹⁷ Beijing Academy of Quantum Information Sciences, Beijing, China. chenjianhao@pku.edu.cn.
¹⁸ Key Laboratory for the Physics and Chemistry of Nanodevices, Peking University, Beijing, China. chenjianhao@pku.edu.cn.
¹⁹ Hefei National Laboratory, Hefei, China. chenjianhao@pku.edu.cn.
²⁰ Collaborative Innovation Center of Quantum Matter, Beijing, China. ye_yu@pku.edu.cn.
²¹ State Key Lab for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing, China. ye_yu@pku.edu.cn.
²² State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, PR China. vitto.han@gmail.com.
²³ Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, PR China. vitto.han@gmail.com.
²⁴ Liaoning Academy of Materials, Shenyang, China. vitto.han@gmail.com.

^# Contributed equally.

Abstract

The realization of graphene gapped states with large on/off ratios over wide doping ranges remains challenging. Here, we investigate heterostructures based on Bernal-stacked bilayer graphene (BLG) atop few-layered CrOCl, exhibiting an over-1-GΩ-resistance insulating state in a widely accessible gate voltage range. The insulating state could be switched into a metallic state with an on/off ratio up to 10⁷ by applying an in-plane electric field, heating, or gating. We tentatively associate the observed behavior to the formation of a surface state in CrOCl under vertical electric fields, promoting electron-electron (e-e) interactions in BLG via long-range Coulomb coupling. Consequently, at the charge neutrality point, a crossover from single particle insulating behavior to an unconventional correlated insulator is enabled, below an onset temperature. We demonstrate the application of the insulating state for the realization of a logic inverter operating at low temperatures. Our findings pave the way for future engineering of quantum electronic states based on interfacial charge coupling.

Grants and funding

92265203/National Natural Science Foundation of China (National Science Foundation of China)