Visualizing the Coulomb blockade in graphene quantum dots, Part I

ORAL

Abstract

The charge of a conductor separated from particle reservoirs by tunnel junctions is quantized in units of the elementary charge, a phenomenon known as Coulomb blockade. Recent experiments have enabled the creation of graphene QDs with fixed build-in potentials inside circular p-n junctions by ionizing impurities in the boron nitride underlying insulator. In these small nanometer sized circular resonators the quasi-bound resonances in zero magnetic field can be confined further by the application of a perpendicular magnetic field forming quantized Landau levels (LL) inside the graphene QD. The LLs at high magnetic fields form a series of metallic rings, separated by highly insulating impressible rings, allowing tunnel barriers to be created between the LL quantum liquids and the sample bias electrode. The isolated LL metallic rings are then accessible by Coulomb blockade spectroscopy between the STM probe and graphene sample. Using scanning tunneling spectroscopy we provide direct spatially and spectroscopically resolved measurements of the formation of the LL rings and their charging characteristics. We investigate the addition energy spectrum of the LL rings and analyze their charging characteristics in terms of capacitances and QD energy level structure.

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Presenters

  • Fereshte Ghahari

    Center for Nanoscale Science and Technology, NIST / Maryland NanoCenter, University of Maryland, Center for Nanoscale Science and Technology, NIST -Natl Inst of Stds & Tech, NIST/University of Maryland, College Park, Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Center for Nanoscale Science and Technology, NIST

Authors

  • Fereshte Ghahari

    Center for Nanoscale Science and Technology, NIST / Maryland NanoCenter, University of Maryland, Center for Nanoscale Science and Technology, NIST -Natl Inst of Stds & Tech, NIST/University of Maryland, College Park, Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Center for Nanoscale Science and Technology, NIST

  • Daniel Walkup

    NIST, Center for Nanoscale Science and Technology, NIST / Maryland NanoCenter, University of Maryland, Center for Nanoscale Science and Technology, NIST -Natl Inst of Stds & Tech, Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Center for Nanoscale Science and Technology, NIST

  • Christopher Gutiérrez

    Center for Nanoscale Science and Technology, NIST

  • Cyprian Lewandowski

    Massachusetts Institute of Technology, Department of Physics, Massachusetts Institute of Technology, Physics Department, Massachusetts Institute of Technology

  • Joaquin Rodriguez Nieva

    Harvard University, Department of Physics, Harvard University, Harvard Univ, Physics Department, Harvard University

  • Kenji Watanabe

    National Institute for Materials Science, NIMS, National Institute for Material Science, Advanced Materials Laboratory, National Institute for Materials Science, National Institute of Materials Science, Research Center for Functional Materials, National Institute for Materials Science, National Institute for Materials Science (NIMS, Advanced Materials Laboratory, NIMS, National Institute for Materials Science, Advanced Materials Laboratory, National Institue for Materials Science, National Institute of Material Science, National Institute for Matericals Science, Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Advanced materials laboratory, National institute for Materials Science, NIMS-Japan

  • Takashi Taniguchi

    National Institute for Materials Science, NIMS, National Institute for Material Science, Advanced Materials Laboratory, National Institute for Materials Science, National Institute of Materials Science, Research Center for Functional Materials, National Institute for Materials Science, National Institute for Materials Science (NIMS, Advanced Materials Laboratory, NIMS, National Institute for Materials Science, Advanced Materials Laboratory, National Institue for Materials Science, National Institute of Material Science, National Institute for Matericals Science, Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, NIMS-Japan

  • Leonid Levitov

    Massachusetts Institute of Technology, Department of Physics, Massachusetts Institute of Technology, Physics, Massachusetts Institute of Technology, Massachusetts Inst of Tech-MIT, MIT, Physics Department, Massachusetts Institute of Technology

  • Nikolai Zhitenev

    Center for Nanoscale Science and Technology, NIST, Center for Nanoscale Science and Technology, NIST -Natl Inst of Stds & Tech, NIST -Natl Inst of Stds & Tech, Center for Nanoscale Science and Technology, National Institute of Standards and Technology

  • Joseph Stroscio

    Center for Nanoscale Science and Technology, NIST, Center for Nanoscale Science and Technology, NIST -Natl Inst of Stds & Tech, NIST -Natl Inst of Stds & Tech, Center for Nanoscale Science and Technology, National Institue of Standards and Technology, Center for Nanoscale Science and Technology, National Institute of Standards and Technology, NIST