Valley-coherent quantum anomalous Hall state in AB-stacked MoTe2/WSe2 bilayers
Abstract
Moir\'e materials provide fertile ground for the correlated and topological quantum phenomena. Among them, the quantum anomalous Hall (QAH) effect, in which the Hall resistance is quantized even under zero magnetic field, is a direct manifestation of the intrinsic topological properties of a material and an appealing attribute for low-power electronics applications. The QAH effect has been observed in both graphene and transition metal dichalcogenide (TMD) moir\'e materials. It is thought to arise from the interaction-driven valley polarization of the narrow moir\'e bands. Here, we show surprisingly that the newly discovered QAH state in AB-stacked MoTe2/WSe2 moir\'e bilayers is not valley-polarized but valley-coherent. The layer- and helicity-resolved optical spectroscopy measurement reveals that the QAH ground state possesses spontaneous spin (valley) polarization aligned (anti-aligned) in two TMD layers. In addition, saturation of the out-of-plane spin polarization in both layers occurs only under high magnetic fields, supporting a canted spin texture. Our results call for a new mechanism for the QAH effect and highlight the potential of TMD moir\'e materials with strong electronic correlations and spin-orbit interactions for exotic topological states.
Keywords
Cite
@article{arxiv.2208.07452,
title = {Valley-coherent quantum anomalous Hall state in AB-stacked MoTe2/WSe2 bilayers},
author = {Zui Tao and Bowen Shen and Shengwei Jiang and Tingxin Li and Lizhong Li and Liguo Ma and Wenjin Zhao and Jenny Hu and Kateryna Pistunova and Kenji Watanabe and Takashi Taniguchi and Tony F. Heinz and Kin Fai Mak and Jie Shan},
journal= {arXiv preprint arXiv:2208.07452},
year = {2022}
}