Loss and decoherence at the quantum Hall - superconductor interface

ORAL

Abstract

High quality type-II superconducting contacts have recently been developed to a variety of 2D systems, allowing one to explore the superconducting proximity in the quantum Hall (QH) regime. Inducing superconducting correlations into a chiral system has long been viewed as a route for creating exotic topological states and excitations. However, it appears that before these exciting predictions could be realized, one should develop a better understanding of the limitations imposed by the physics of real materials. Here, we perform a systematic study of Andreev conversion at the interface between a superconductor and graphene in the QH regime. We find that the probability of Andreev conversion of electrons to holes follows an unexpected but clear trend: the dependencies on temperature and magnetic field are nearly decoupled. We discuss these trends and the role of the superconducting vortices, whose normal cores could both absorb and dephase the individual electrons in a QH edge. Our study may pave the road to engineering future generation of hybrid devices for exploiting superconductivity proximity in chiral channels.

*Sample fabrication and transport measurements by L.Z. were supported by NSF award DMR-2004870. Project discussion by Z.I., T.L. and E.A., as well as the guidance by G.F. were supported by the Division of Materials Sciences and Engineering, Office of Basic Energy Sciences, U.S. Department of Energy, under Award No. DE-SC0002765. The deposition of MoRe performed by F.A. was supported by a URC grant at Appalachian State University. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan, (grant no. JPMXP0112101001), JSPS KAKENHI (grant no. JP20H00354) and CREST (no. JPMJCR15F3, JST). The sample fabrication was performed in part at the Duke University Shared Materials Instrumentation Facility (SMIF), a member of the North Carolina Research Triangle Nanotechnology Network (RTNN), which is supported by the National Science Foundation (Grant ECCS-1542015) as part of the National Nanotechnology Coordinated Infrastructure (NNCI).

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Presenters

  • Lingfei Zhao

    • Duke University

Authors

  • Lingfei Zhao

    • Duke University

  • Zubair Iftikhar

    • Duke University

  • Trevyn Larson

    • Duke University

  • Ethan G Arnault

    • MIT Research Laboratory of Electronics
    • Duke University
    • Massachusetts Institute of Technology

  • Kenji Watanabe

    • National Institute for Materials Science
    • Research Center for Functional Materials, National Institute of Materials Science
    • Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-044, Japan
    • NIMS
    • Research Center for Functional Materials, National Institute for Materials Science
    • National Institute for Materials Science, Japan
    • Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
    • NIMS Japan

  • Takashi Taniguchi

    • National Institute for Materials Science
    • Kyoto Univ
    • International Center for Materials Nanoarchitectonics, National Institute of Materials Science
    • Kyoto University
    • International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-044, Japan
    • International Center for Materials Nanoarchitectonics, National Institute for Materials Science
    • National Institute for Materials Science, Japan
    • National Institute For Materials Science
    • NIMS
    • National Institute for Material Science
    • International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
    • NIMS Japan

  • Francois Amet

    • Appalachian State University

  • Gleb Finkelstein

    • Duke University