• 文献标题:   Twisting dirac fermions: circular dichroism in bilayer graphene
  • 文献类型:   Article
  • 作  者:   MORELL ES, CHICO L, BREY L
  • 作者关键词:   graphene, twisted bilayer, circular dichroism
  • 出版物名称:   2D MATERIALS
  • ISSN:   2053-1583
  • 通讯作者地址:   Consejo Super Invest Cient ICMM CSIC
  • 被引频次:   4
  • DOI:   10.1088/2053-1583/aa7eb6
  • 出版年:   2017

▎ 摘  要

Twisted bilayer graphene is a chiral system which has been recently shown to present circular dichroism. In this work we show that the origin of this optical activity is the rotation of the Dirac fermions' helicities in the top and bottom layer. Starting from the Kubo formula, we obtain a compact expression for the Hall conductivity that takes into account the dephasing of the electromagnetic field between the top and bottom layers and gathers all the symmetries of the system. Our results are based in both a continuum and a tight-binding model, and they can be generalized to any two-dimensional Dirac material with a chiral stacking between layers.