Size quantization of Dirac fermions in graphene constrictions

B. Terrés, L. A. Chizhova, F. Libisch, J. Peiro, D. Jörger, S. Engels, A. Girschik, K. Watanabe, T. Taniguchi, S. V. Rotkin, J. Burgdörfer, C. Stampfer

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Abstract

Quantum point contacts are cornerstones of mesoscopic physics and central building blocks for quantum electronics. Although the Fermi wavelength in high-quality bulk graphene can be tuned up to hundreds of nanometres, the observation of quantum confinement of Dirac electrons in nanostructured graphene has proven surprisingly challenging. Here we show ballistic transport and quantized conductance of size-confined Dirac fermions in lithographically defined graphene constrictions. At high carrier densities, the observed conductance agrees excellently with the Landauer theory of ballistic transport without any adjustable parameter. Experimental data and simulations for the evolution of the conductance with magnetic field unambiguously confirm the identification of size quantization in the constriction. Close to the charge neutrality point, bias voltage spectroscopy reveals a renormalized Fermi velocity of â 141.5 × 10 6 m s â 1 in our constrictions. Moreover, at low carrier density transport measurements allow probing the density of localized states at edges, thus offering a unique handle on edge physics in graphene devices.

Original languageEnglish (US)
Article number11528
JournalNature communications
Volume7
DOIs
StatePublished - May 20 2016

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

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    Terrés, B., Chizhova, L. A., Libisch, F., Peiro, J., Jörger, D., Engels, S., Girschik, A., Watanabe, K., Taniguchi, T., Rotkin, S. V., Burgdörfer, J., & Stampfer, C. (2016). Size quantization of Dirac fermions in graphene constrictions. Nature communications, 7, [11528]. https://doi.org/10.1038/ncomms11528