Valley-coherent quantum anomalous Hall state in AB-stacked MoTe2/WSe2 bilayers
ORAL
Abstract
Moire´ 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) moire´ materials. It is thought to arise from the interaction-driven valley polarization of the narrow moire´ bands. Here, we show surprisingly that the newly discovered QAH state in AB-stacked MoTe2/WSe2 moire´ 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 moire´ materials with strong electronic correlations and spin-orbit interactions for exotic topological states.
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Presenters
Zui Tao
Cornell University
Authors
Zui Tao
Cornell University
Bowen Shen
Cornell University
Shengwei Jiang
Shanghai Jiaotong university
Tingxin Li
Shanghai Jiao Tong University
Shanghai Jiaotong University
Lizhong Li
Cornell University
Liguo Ma
Fudan Univ
Cornell University
Wenjin Zhao
Cornell University, Kavli Institute at Cornell
Jenny Hu
Stanford University
Stanford Univ
Kateryna Pistunova
Stanford Univ
Kenji Watanabe
National Institute for Materials Science
Research Center for Functional Materials, National Institute of Materials Science
Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-044, Japan
NIMS
Research Center for Functional Materials, National Institute for Materials Science
National Institute for Materials Science, Japan
Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
NIMS Japan
Takashi Taniguchi
National Institute for Materials Science
Kyoto Univ
International Center for Materials Nanoarchitectonics, National Institute of Materials Science
Kyoto University
International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-044, Japan
International Center for Materials Nanoarchitectonics, National Institute for Materials Science
National Institute for Materials Science, Japan
National Institute For Materials Science
NIMS
National Institute for Material Science
International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
