Edge currents shunt the insulating bulk in gapped graphene

M. J. Zhu, Andrey Kretinin, M.D. Thompson, Denis Bandurin, Shuang Hu, G.L. Yu, John Birkbeck, Artem Mishchenko, Ivan J. Vera-Marun, K. Watanabe, T Taniguchi, M Polini, J. R. Prance, Konstantin Novoselov, Andre Geim, Moshe Ben Shalom

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    Abstract

    An energy gap can be opened in the spectrum of graphene reaching values as large as 0.2 eV in the case of bilayers. However, such gaps rarely lead to the highly insulating state expected at low temperatures. This long-standing puzzle is usually explained by charge inhomogeneity. Here we revisit the issue by investigating proximity-induced superconductivity in gapped graphene and comparing normal-state measurements in the Hall bar and Corbino geometries. We find that the supercurrent at the charge neutrality point in gapped graphene propagates along narrow channels near the edges. This observation is corroborated by using the edgeless Corbino geometry in which case resistivity at the neutrality point increases exponentially with increasing the gap, as expected for an ordinary semiconductor. In contrast, resistivity in the Hall bar geometry saturates to values of about a few resistance quanta. We attribute the metallic-like edge conductance to a nontrivial topology of gapped Dirac spectra.
    Original languageEnglish
    Article number14552
    JournalNature Communications
    Volume8
    Early online date17 Feb 2017
    DOIs
    Publication statusPublished - 2017

    Research Beacons, Institutes and Platforms

    • National Graphene Institute

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