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research article

Tilted double Dirac cone and anisotropic quantum-spin-Hall topological insulator in mechanical granular graphene

Zheng, Li-Yang
•
Theocharis, Georgios
•
Fleury, Romain  
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October 7, 2020
New Journal of Physics

Dirac degeneracies are essential ingredients to control topological charge exchanges between bands and trigger the unique edge transport properties of topological materials. In addition, when Dirac cones are tilted, exotic phenomena can emerge such as anomalous Hall effect or unconventional Klein tunneling. However, the unique topological transport properties arising from the opening of tilted Dirac cone degeneracies have been left completely uncharted. Here, we demonstrate a new form of Dirac degeneracy that occurs in mechanical granular graphene (MGG): a tilted double Dirac cone, composed of two counter-tilted type-I Dirac cones. Different from the reported C 6 systems, we show that the tilted double Dirac cone is present in a C 2 granular graphene. Remarkably, a pair of anisotropic helical edge waves appears when the degeneracy is lifted. This leads to an anisotropic quantum spin-Hall topological insulator that possesses unique wave propagation properties, including anisotropic edge dispersion and direction-dependent edge-bulk mode conversion.

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Type
research article
DOI
10.1088/1367-2630/abb862
Author(s)
Zheng, Li-Yang
•
Theocharis, Georgios
•
Fleury, Romain  
•
Tournat, Vincent
•
Gusev, Vitalyi
Date Issued

2020-10-07

Published in
New Journal of Physics
Volume

22

Issue

10

Article Number

103012

Subjects

granular media

•

topological insulator

Note

Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence.

Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LWE  
Available on Infoscience
October 13, 2020
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/172434
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