• 文献标题:   Nano-photocurrent Mapping of Local Electronic Structure in Twisted Bilayer Graphene
  • 文献类型:   Article
  • 作  者:   SUNKU SS, MCLEOD AS, STAUBER T, YOO H, HALBERTAL D, NI GX, STERNBACH A, JIANG BY, TANIGUCHI T, WATANABE K, KIM P, FOGLER MM, BASOV DN
  • 作者关键词:   twisted bilayer graphene, moire superlattice, photothermoelectric effect, nanophotocurrent, scanning nearfield microscopy, interband transition
  • 出版物名称:   NANO LETTERS
  • ISSN:   1530-6984 EI 1530-6992
  • 通讯作者地址:   Columbia Univ
  • 被引频次:   4
  • DOI:   10.1021/acs.nanolett.9b04637
  • 出版年:   2020

▎ 摘  要

We report a combined nano-photocurrent and infrared nanoscopy study of twisted bilayer graphene (TBG) enabling access to the local electronic phenomena at length scales as short as 20 nm. We show that the photocurrent changes sign at carrier densities tracking the local superlattice density of states of TBG. We use this property to identify domains of varying local twist angle by local photothermoelectric effect. Consistent with the photocurrent study, infrared nanoimaging experiments reveal optical conductivity features dominated by twist-angle-dependent interband transitions. Our results provide a fast and robust method for mapping the electronic structure of TBG and suggest that similar methods can be broadly applied to probe electronic inhomogeneities of Moire superlattices in other van der Waals heterostructures.