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Observation of large Zeeman-like splitting in graphene whispering gallery modes

ORAL

Abstract

Monolayer graphene (MLG) hosts massless Dirac fermions with a linear band dispersion that mimics photons. Because of these attributes and its ballistic transport in ultraclean samples, MLG is an ideal platform for the development of electron optic devices. To date, multiple electron optic effects have been experimentally demonstrated in electrostatic MLG pn junctions such as Fabry-Pérot interference, whispering gallery mode (WGM) resonances, and negative electron refraction. Crucially, the MLG pn junction sharpness can significantly affect the transmission probability of its chiral charge carriers across the pn junction. In this talk, I will show our recent scanning tunneling spectroscopy (STS) study of MLG quantum dots defined by circular pn junctions with different pn junction sharpness. By increasing the sharpness of the pn junction, we observe a strong increase in the quality (Q) factor of the WGMs near the pn junction boundary. Furthermore, we observe large and gate tunable Zeeman-like linear splitting of these high Q factor WGMs in a small magnetic field due to their large orbital magnetic moments. Our work indicates graphene WGMs in sharp circular pn junctions can be used for tunable magnetic field sensors.  

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Presenters

  • Zhehao Ge

    Department of Physics, University of California, Santa Cruz, University of California, Santa Cruz

Authors

  • Zhehao Ge

    Department of Physics, University of California, Santa Cruz, University of California, Santa Cruz

  • Sergey Slizovskiy

    Department of Physics and Astronomy, University of Manchester, Univ of Manchester

  • Toyanath Joshi

    Department of Physics, University of California, Santa Cruz, University of California, Santa Cruz, Physics Department, University of California, Santa Cruz, CA

  • Takashi Taniguchi

    National Institute for Materials Science, Tsukuba, Japan, National Institute for Materials Science, NIMS, Kyoto Univ, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Ibaraki 305-0044, Japan., 3 National Institute for Materials Science, Tsukuba, Japan, National Institute for Materials Science; 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan, National Institute of Materials Science, Tsukuba, Japan, National Institute of Materials Science, Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan, National Institute for Materials Science (Japan), International Center for Materials Nanoarchitectonics, National Institute for Materials Science, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, Kyoto University, International Center for Materials Nanoarchitectonics, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Japan, International Center for Materials Nanoarchitectonics, National Institute for MaterialsScience, 1-1 Namiki, Tsukuba 305-0044, Japan, National Institute for Material Science, Japan, National Institute for Material Science, National Institute of Material Sciences, Japan, NIMS, Tsukuba, 2National Institute for Materials Science, Namiki 1-1, Ibaraki 305-0044, Japan., National Institute of Materials Science, Tsukuba, Ibaraki 305-0044, Japan, National Institute for Materials Science, Japan, International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan., NIMS, Japan, National Institute for Materials Science (NIMS), NIMS. Japan, International Center for Material Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan, International Center for Material Nanoarchitectonics, National Institute for Materials Science, National Institute for Materials Science Tsukuba, National Institute for Materials Science, 1-1 Namiki, National Institute for Materials Science of Japan, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, NIMS - National Institute for Material Science, Japan, International Center for Materials Nanoarchitectonics, National Institute for Material Science, Tsukuba, Ibaraki 305-0044, Japan., National Institute for Material Science, Tsukuba, National Institute for Materials Science, International Center for Materials Nanoarchitectonics, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan, National Institute of Material Science, National Institute for Materials Science,1-1 Namiki, Tsukuba, 305-0044, Japan

  • Kenji Watanabe

    National Institute for Materials Science, Tsukuba, Japan, National Institute for Materials Science, NIMS, Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan, Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan., Research Center for Functional Materials, National Institute for Materials Science, Advanced, Materials Laboratory, NIMS, 3 National Institute for Materials Science, Tsukuba, Japan, National Institute for Materials Science; 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan, National Institute of Materials Science, Tsukuba, Japan, National Institute of Materials Science, Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan, National Institute for Materials Science (Japan), National Institute for Materials Science, Japan, Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, Research Center for Functional Materials, Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan, Research Center for Functional Materials, National Institute for Materials Science, Japan, Research Center for Functional Materials, National Institute for Materials Science, 1-1Namiki, Tsukuba 305-0044, Japan, National Institute for Material Science, Japan, National Institute for Material Science, National Institute of Material Sciences, Japan, NIMS, Tsukuba, 2National Institute for Materials Science, Namiki 1-1, Ibaraki 305-0044, Japan., National Institute of Materials Science, Tsukuba, Ibaraki 305-0044, Japan, National Institute for Materials Science Japan, NIMS, Japan, nims, National Institute for Materials Science, Research Center for Functional Materials, Japan, National Institute for Materials Science Tsukuba, National Institute for Materials Science, 1-1 Namiki, National Institute for Materials Science of Japan, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, NIMS - National Institute for Material Science, Japan, Research Center for Functional Materials, National Institute for Material Science, Tsukuba, Ibaraki, 305-0044, Japan., National Institute for Material Science, Tsukuba, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan, National Institute for Materials Science (NIMS), National Institute for Materials Science, Research Center for Functional Materials, Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan, National Institute of Material Science, Kyoto Univ, National Institute for Materials Science,1-1 Namiki, Tsukuba, 305-0044, Japan

  • David Lederman

    Department of Physics, University of California, Santa Cruz, University of California, Santa Cruz, Physics Department, University of California, Santa Cruz

  • Vladimir Falko

    Department of Physics and Astronomy, University of Manchester, The University of Manchester, Manchester University

  • Jairo Velasco

    Department of Physics, University of California, Santa Cruz, University of California, Santa Cruz