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Electrostatically Induced Quantum Point Contacts in Bilayer Graphene
journal contribution
posted on 2017-12-29, 16:13 authored by Hiske Overweg, Hannah Eggimann, Xi Chen, Sergey Slizovskiy, Marius Eich, Riccardo Pisoni, Yongjin Lee, Peter Rickhaus, Kenji Watanabe, Takashi Taniguchi, Vladimir Fal’ko, Thomas Ihn, Klaus EnsslinWe
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.− 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.