Unconventional Josephson Effect in a topological Kondo insulator

ORAL

Abstract

Proximity-induced superconductivity in three dimensional (3D) topological insulators forms a new quantum phase of matter and harbors exotic quasiparticles such as Majorana bound states. One of the biggest drawbacks of the commonly studied 3D topological insulators is having conducting bulk that obscures the role of surface states. Introducing superconductivity in topological Kondo insulators such as SmB6 is particularly promising due to their robust insulating bulk at low temperatures. In this work, we develop an unconventional Josephson junction by coupling superconducting Nb leads to the surface states of a SmB6 crystal. We observe a distinct critical current at low temperatures that exhibits a Fraunhofer diffraction pattern with the application of an out-of-plane magnetic field. The appearance of Shaphiro steps under microwave irradiation gives further evidence of a Josephson Effect. The Fraunhofer patterns show an anomalous hysteresis with magnetic field sweep direction suggesting coexistence of ferromagnetism with superconductivity in the topological surface states of SmB6. The experimental work will advance the current understanding of topologically nontrivial superconductors and emergent states associated with such unconventional superconducting phases.

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Presenters

  • Cihan Kurter

    • IBM Thomas J. Watson Research Center

Authors

  • Xuecheng Ye

    • Physics, Missouri University of Science and Technology

  • Jacob Cook

    • Physics, University of Missouri

  • Erik Huemiller

    • Physics, University of Illinois at Urbana-Champaign
    • Inprentus Precision Optics
    • Physics, University of Illinois Urbana Champaign
    • University of Illinois at Urbana-Champaign

  • Aaron D Finck

    • IBM Thomas J. Watson Research Center

  • Pouyan Ghaemi Mohammadi

    • Physics, The City College of New York, CUNY
    • Physics, City College of City University of New York
    • City College of New York
    • Physics, City College of New York,New York, NY 10031

  • Thomas Vojta

    • Department of Physics, Missouri University of Science and Technology
    • Physics, Missouri University of Science and Technology
    • Missouri University of Science and Technology

  • Shanta Saha

    • Physics, University of Maryland
    • Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland
    • University of Maryland, College Park & NIST
    • Department of Physics, University of Maryland, College Park
    • University of Maryland
    • University of Maryland - College Park

  • Johnpierre Paglione

    • Physics, University of Maryland
    • University of Maryland, College Park
    • Center for Nanophysics and Advanced Materials, University of Maryland College Park
    • Center for Nanophysics and Advance Materials, University of Maryland, College Park, MD
    • University of Maryland, College Park & NIST
    • Department of Physics, University of Maryland, College Park
    • University of Maryland
    • University of Maryland - College Park

  • Cihan Kurter

    • IBM Thomas J. Watson Research Center