Twisting Dirac fermions: Circular dichroism in bilayer graphene
Materials Science
2017-09-18 v2
Abstract
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.
Keywords
Cite
@article{arxiv.1705.07742,
title = {Twisting Dirac fermions: Circular dichroism in bilayer graphene},
author = {E. Suarez Morell and Leonor Chico and Luis Brey},
journal= {arXiv preprint arXiv:1705.07742},
year = {2017}
}