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arXiv · 1802.02999

Topologically Protected Helical States in Minimally Twisted Bilayer Graphene

Shengqiang Huang·Kyounghwan Kim·Dmitry K. Efimkin·Timothy Lovorn·Takashi Taniguchi·Kenji Watanabe·Allan H. MacDonald·Emanuel Tutuc·Brian J. LeRoy
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Abstract

In minimally twisted bilayer graphene, a moir{\'e} pattern consisting of AB and BA stacking regions separated by domain walls forms. These domain walls are predicted to support counterpropogating topologically protected helical (TPH) edge states when the AB and BA regions are gapped. We fabricate designer moir{\'e} crystals with wavelengths longer than 50 nm and demonstrate the emergence of TPH states on the domain wall network by scanning tunneling spectroscopy measurements. We observe a double-line profile of the TPH states on the domain walls, only occurring when the AB and BA regions are gapped. Our results demonstrate a practical and flexible method for TPH state network construction.

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Shengqiang Huang, Kyounghwan Kim, Dmitry K. Efimkin, Timothy Lovorn, Takashi Taniguchi, Kenji Watanabe, Allan H. MacDonald, Emanuel Tutuc, Brian J. LeRoy. 2018-02-08. Topologically Protected Helical States in Minimally Twisted Bilayer Graphene. https://doi.org/10.1103/physrevlett.121.037702

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