Singularities and topologically protected states in twisted bilayer graphene

Qirong Yao*, Xingchen Chen, Rik Van Bremen, Kai Sotthewes, Harold J.W. Zandvliet

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

We have studied the structural and electronic properties of twisted bilayer graphene by scanning tunneling microscopy (STM). For twist angles in the range of about 1° to 4°, the twisted bilayer graphene possesses two Van Hove singularities in the vicinity of the Fermi level. We use the exact location of these Van Hove singularities to determine the twist angle dependent interlayer hopping energy. For a twist angle of 0.6°, we found a hexagonal network of topologically protected one-dimensional channels that run along the boundaries of the AB/BA domains. The electric field in the tunnel junction is responsible for the breaking of the symmetry of the AB and BA domains and the development of the hexagonal network of topologically protected states. The latter shows that the electric field in the tunneling junction can significantly affect the topological nature of two-dimensional materials, and therefore, one should be cautious when interpreting scanning tunneling microscopy and spectroscopy experiments of this class of materials.

Original languageEnglish
Article number011602
Number of pages4
JournalApplied physics letters
Volume116
Issue number1
Early online date8 Jan 2020
DOIs
Publication statusE-pub ahead of print/First online - 8 Jan 2020

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