Perfect one-dimensional chiral states in biased twisted bilayer graphene

We theoretically study the electronic structure of small-angle twisted bilayer graphene with a large potential asymmetry between the top and bottom layers. We show that the emergent helical states known to appear on the triangular AB-BA domain boundary do not actually form a percolating network, but...

Full description

Saved in:
Bibliographic Details
Published in:arXiv.org 2020-01
Main Authors: Tsim, Bonnie, Nam, Nguyen N T, Koshino, Mikito
Format: Article
Language:English
Subjects:
Bilayers
Channels
Deformation effects
Electronic structure
Graphene
Monolayers
Percolation
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We theoretically study the electronic structure of small-angle twisted bilayer graphene with a large potential asymmetry between the top and bottom layers. We show that the emergent helical states known to appear on the triangular AB-BA domain boundary do not actually form a percolating network, but instead they provide independent, perfect one-dimensional channels propagating in three different directions. Using the continuum-model Hamiltonian, we demonstrate that an applied bias causes two well-defined energy windows which contain sparsely distributed one-dimensional channels. The origin of these energy windows can be understood using a two-band model of the intersecting electron and hole bands of single layer graphene. We also use the tight-binding model to implement the lattice deformations in twisted bilayer graphene, and discuss the effect of lattice relaxation on the one-dimensional channels.
ISSN:2331-8422
DOI:10.48550/arxiv.2001.06257