Chiral zigzag modes and flatbands in network models of twisted bilayer graphene

We construct a phenomenological scattering theory for the triangular network of valley Hall states that arises in twisted bilayer graphene under interlayer bias. Crucially, our network model includes scattering between different valley Hall states within the same valley and spin. We show that in the...

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Bibliographic Details
Published in:arXiv.org 2020-05
Main Authors: De Beule, C, Dominguez, F, Recher, P
Format: Article
Language:English
Subjects:
Bilayers
Fermi surfaces
Forward scattering
Graphene
Interlayers
Nesting
Online Access:Get full text
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Summary:We construct a phenomenological scattering theory for the triangular network of valley Hall states that arises in twisted bilayer graphene under interlayer bias. Crucially, our network model includes scattering between different valley Hall states within the same valley and spin. We show that in the absence of forward scattering, symmetries reduce the network model to a single parameter that interpolates between a nested Fermi surface and flatbands, which can be understood in terms of one-dimensional chiral zigzag modes and closed triangular orbits, respectively. We demonstrate how unitarity and symmetry constrain the couplings between zigzag modes, which has important implications on the nature of interference oscillations observed in experiments.
ISSN:2331-8422
DOI:10.48550/arxiv.2003.08987