Crossed Andreev reflection in the fractional quantum Hall state of graphene

ORAL

Abstract

We construct high-quality graphene-based van der Waals devices with narrow superconducting niobium nitride (NbN) electrodes, in which superconductivity and robust fqH can coexist. We find crossed Andreev reflection (CAR) across the superconductor separating two qH edges. In integer fillings, we find a filling-independent CAR probability robust to changes in magnetic field and temperature, which we attribute to spin-orbit coupling in NbN allowing for Andreev reflection between spin-polarized edges. Interestingly, while CAR in the hole-conjugate fractions has similar behavior, CAR probabilities in the particle-like fractional fillings are markedly higher and depend strongly on temperature and magnetic field. We investigate this behavior by tuning the doping of the NbN interface while keeping bulk filling constant. These results provide a route to realize novel topological superconducting phases in fqH–superconductor hybrid devices based on graphene and NbN.

*Ö.G. acknowledges support by a Rubicon grant of the Netherlands Organization for Scientific Research (NWO). Y.R. and P.K. acknowledge support from DOE (DE-SC0012260) for measurement and analysis, and NSF (QII-TAQS MPS 1936263) for characterization. S.Y.L. and Y.H.L. acknowledge support from the Institute for Basic Science (IBS-R011-D1). H.S. and A.V. acknowledge support by the Simons Collaboration on Ultra-Quantum Matter, a grant from the Simons Foundation (651440, A.V.). J.Z. and A.Y. acknowledge support from DOE (DE-SC0019300) for device fabrication. A.Y. acknowledges funding from NSF DMR-1708688. P.K. and A.Y. acknowledge support from Science and Technology Center for Integrated Quantum Materials, NSF Grant No. DMR-1231319. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan (JPMXP0112101001) and JSPS KAKENHI (19H05790 and JP20H00354). Nanofabrication was performed at the Center for Nanoscale Systems at Harvard, supported in part by

–

Publication: Gul, Ö. et al. Andreev reflection in the fractional quantum Hall state. Preprint at https://arxiv.org/abs/2009.07836 (2021).

Presenters

  • Jonathan Zauberman

    • Harvard University

Authors

  • Jonathan Zauberman

    • Harvard University

  • Onder Gul

    • Harvard University

  • Yuval Ronen

    • Harvard University

  • Si Young Lee

    • Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University

  • Hassan Shapourian

    • Microsoft Corp

  • Jonathan Zauberman

    • Harvard University

  • Young Hee Lee

    • Sungkyunkwan University
    • Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University
    • sungkyunkwan university, suwon, korea
    • Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon 16419, Republic of Korea

  • 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

  • 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

  • Ashvin Vishwanath

    • Harvard University

  • Amir Yacoby

    • Harvard University

  • Philip Kim

    • Harvard University