Topological valley currents via ballistic edge modes in graphene superlattices near the primary Dirac point

Yang Li*, Mario Amado, Timo Hyart, Grzegorz P. Mazur, Jason W.A. Robinson

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

Graphene on hexagonal boron nitride (hBN) can exhibit a topological phase via mutual crystallographic alignment. Recent measurements of nonlocal resistance (Rnl) near the secondary Dirac point (SDP) in ballistic graphene/hBN superlattices have been interpreted as arising due to the quantum valley Hall state. We report hBN/graphene/hBN superlattices in which Rnl at SDP is negligible, but below 60 K approaches the value of h/2e2 in zero magnetic field at the primary Dirac point with a characteristic decay length of 2 μm. Furthermore, nonlocal transport transmission probabilities based on the Landauer-Büttiker formalism show evidence for spin-degenerate ballistic valley-helical edge modes, which are key for the development of valleytronics.

Original languageEnglish
Article number224
Number of pages7
JournalCommunications physics
Volume3
Issue number1
DOIs
Publication statusPublished - 4 Dec 2020
MoE publication typeA1 Journal article-refereed

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