Valley-symmetry-preserved transport in ballistic graphene with gate-defined carrier guiding

Minsoo Kim, Ji Hae Choi, Sang Hoon Lee, Kenji Watanabe, Takashi Taniguchi, Seung Hoon Jhi, Hu Jong Lee

    Research output: Contribution to journalLetterpeer-review

    Abstract

    Ever since the discovery of graphene, valley symmetry and its control in the material have been a focus of continued studies in relation to valleytronics. Carrier-guiding quasi-one-dimensional (1D) graphene nanoribbons (GNRs) with quantized energy subbands preserving the intrinsic Dirac nature have provided an ideal system to that end. Here, by guiding carriers through dual-gate operation in high-mobility monolayer graphene, we report the realization of quantized conductance in steps of 4e 2 /h in zero magnetic field, which arises from the full symmetry conservation of quasi-1D ballistic GNRs with effective zigzag-edge conduction. A tight-binding model calculation confirms conductance quantization corresponding to zigzag-edge conduction even for arbitrary GNR orientation. Valley-symmetry conservation is further confirmed by intrinsic conductance interference with a preserved Berry phase of € in a graphene-based Aharonov-Bohm (AB) ring prepared by similar dual gating. This top-down approach for gate-defined carrier guiding in ballistic graphene is of particular relevance in the efforts towards efficient and promising valleytronic applications.

    Original languageEnglish
    Pages (from-to)1022-1026
    Number of pages5
    JournalNature Physics
    Volume12
    Issue number11
    DOIs
    Publication statusPublished - 1 Nov 2016

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