• 文献标题:   Moire Band Topology in Twisted Bilayer Graphene
  • 文献类型:   Article
  • 作  者:   MA C, WANG QY, MILLS S, CHEN XL, DENG BC, YUAN SF, LI C, WATANABE K, TANIGUCHI T, DU X, ZHANG F, XIA FN
  • 作者关键词:   twisted bilayer graphene, band topology, nonlocal resistance, superlattice gap, moire band, z 2 invariant
  • 出版物名称:   NANO LETTERS
  • ISSN:   1530-6984 EI 1530-6992
  • 通讯作者地址:   Yale Univ
  • 被引频次:   2
  • DOI:   10.1021/acs.nanolett.0c02131
  • 出版年:   2020

▎ 摘  要

Recently twisted bilayer graphene (t-BLG) has emerged as a strongly correlated physical platform. Besides the apparent significance of band flatness, band topology may be another critical element in t-BLG and yet receives much less attention. Here we report the compelling evidence for nontrivial noninteracting Moire band topology in t-BLG through a systematic nonlocal transport study and a K-theory examination. The nontrivial topology manifests itself as two pronounced nonlocal responses in the electron and hole superlattice gaps. We show that the nonlocal responses are robust to the twist angle and edge termination, exhibiting a universal scaling law. We elucidate that, although Berry curvature is symmetry-trivialized, two nontrivial Z(2) invariants characterize the Moire Dirac bands, validating the topological origin of the observed nonlocal responses. Our findings not only provide a new perspective for understanding the strongly correlated t-BLG but also suggest a potential strategy to achieve topological metamaterials from trivial vdW materials.