Quantum Hall phase in graphene engineered by interfacial charge coupling
Yaning Wang, Xiang Gao, Kaining Yang, Pingfan Gu, Xin Lü, Shihao Zhang, Yuchen Gao, Naijie Ren, Baojuan Dong, Yuhang Jiang, Kenji Watanabe, Takashi Taniguchi, Jun Kang, Wenkai Lou, Jinhai Mao, Jianpeng Liu, Yu Ye, Zheng Han, Kai Chang, Jing Zhang, Zhidong Zhang
Abstract
Abstract The quantum Hall effect can be substantially affected by interfacial coupling between the host two-dimensional electron gases and the substrate, and has been predicted to give rise to exotic topological states. Yet the understanding of the underlying physics and the controllable engineering of this interaction remains challenging. Here we demonstrate the observation of an unusual quantum Hall effect, which differs markedly from that of the known picture, in graphene samples in contact with an antiferromagnetic insulator CrOCl equipped with dual gates. Two distinct quantum Hall phases are developed, with the Landau levels in monolayer graphene remaining intact at the conventional phase, but largely distorted for the interfacial-coupling phase. The latter quantum Hall phase is even present close to the absence of a magnetic field, with the consequential Landau quantization following a parabolic relation between the displacement field and the magnetic field. This characteristic prevails up to 100 K in a wide effective doping range from 0 to 10 13 cm −2 .