Anomalous Gate-tunable Capacitance in Van der Waals Heterostructures

Linshang Chen; Haoran Long; Heng Wu; Rui Mei; Zhengyu Su; Mengjie Feng; Jiang-Bin Wu; Kenji Watanabe; Takashi Taniguchi; Xuewei Cao; Zhongming Wei; Ping-Heng Tan; Yanmeng Shi

arXiv · 2405.03976

Anomalous Gate-tunable Capacitance in Van der Waals Heterostructures

Linshang Chen·Haoran Long·Heng Wu·Rui Mei·Zhengyu Su·Mengjie Feng·Jiang-Bin Wu·Kenji Watanabe·Takashi Taniguchi·Xuewei Cao·Zhongming Wei·Ping-Heng Tan·Yanmeng Shi

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Abstract

The ferroelectricity emerging in non-polar graphene/hexagonal boron nitride (hBN) heterostructures has drawn considerable attention because of its fascinating properties and promising high-frequency electrical polarization switching. Yet, the underlying mechanism is still under debate. Here in twisted double bilayer graphene (TDBLG) aligned with its neighboring hBN, we observed two types of hysteresis - delayed hysteresis in top gate induced by the anomalous screening, and advanced hysteresis in back gate caused by the anomalous gate-tunable capacitance. To investigate the role played by moir\'e potential in the anomalous hysteresis, we studied a moir\'eless graphene heterostructure as control experiment. Unexpectedly, we observed exactly the same phenomena in this control device. Our findings suggest that the anomalous ferroelectricity in graphene/hBN heterostructures may originate from the dielectric material hBN, calling for further structural investigations on hBN. The observation of gate-tunable capacitance provides more insights in the mysterious ferroelectricity in graphene/hBN heterostructures, and should enable new design of memory devices such as memcapacitor based on tunable capacitance.

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Linshang Chen, Haoran Long, Heng Wu, Rui Mei, Zhengyu Su, Mengjie Feng, Jiang-Bin Wu, Kenji Watanabe, Takashi Taniguchi, Xuewei Cao, Zhongming Wei, Ping-Heng Tan, Yanmeng Shi. 2024-05-07. Anomalous Gate-tunable Capacitance in Van der Waals Heterostructures. https://arxiv.org/abs/2405.03976

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