Electrostatically Induced Quantum Point Contacts in Bilayer Graphene

Hiske Overweg, Hannah Eggimann, Xi Chen, Sergey Slizovskiy, Marius Eich, Riccardo Pisoni, Yongjin Lee, Peter Rickhaus, Kenji Watanabe, Takashi Tanaguchi, Vladimir Fal'ko, Thomas Ihn, Klaus Ensslin

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    Abstract

    We report the fabrication of electrostatically defined nanostructures in encapsulated bilayer graphene, with leakage resistances below depletion gates as high as R ∼ 10 GΩ. This exceeds previously reported values of R = 10–100 kΩ.1−3 We attribute this improvement to the use of a graphite back gate. We realize two split gate devices which define an electronic channel on the scale of the Fermi-wavelength. A channel gate covering the gap between the split gates varies the charge carrier density in the channel. We observe device-dependent conductance quantization of ΔG = 2e2/h and ΔG = 4e2/h. In quantizing magnetic fields normal to the sample plane, we recover the four-fold Landau level degeneracy of bilayer graphene. Unexpected mode crossings appear at the crossover between zero magnetic field and the quantum Hall regime.

    Original languageEnglish
    JournalNano Letters
    DOIs
    Publication statusPublished - 29 Dec 2017

    Research Beacons, Institutes and Platforms

    • National Graphene Institute

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