Unconventional superconductivity in iron-based van der Waals heterostructures

ORAL

Abstract

High-temperature superconductivity is a holy grail of condensed matter physics. It shifts the conventional BCS paradigm and opens an appealing future for application. In this context, iron-based superconductors (FeSC) play a vital role in understanding unconventional superconductivity in multiorbital systems. Moreover, the interplay between strong electronic correlations, magnetism, nematicity, and band topology gives rise to universal sign-changed superconducting pairing orders accompanied by a rich phase diagram that depends on the exact compound composition. For these reasons, making a unified theoretical description of superconductivity in this system is still challenging. Previous measurements of FeSC were mainly focused on macroscopic-size samples, while potentially significant quantum effects in finite-size samples have yet to be explored. In this talk, we discuss fabricated van der Waals structures based on exfoliated thin flakes of FeSC. Using scanning tunneling microscopy and spectroscopy, we discovered modulation of superconductivity, in huge contrast with its bulk crystal counterpart. We further discussed several possible mechanisms for the origin of the exotic behaviors with the help of a microscopic model. Our results reveal new insights into the unconventional nature of FeSC and provide a novel method to study other unconventional superconductors.

*We acknowledge the support of the Institute for Quantum Information and Matter, an NSF Physics Frontiers Center with support of the Gordon and Betty Moore Foundation through grant no. GBMF1250. L. K acknowledges support of the IQIM/AWS Quantum postdoctoral fellowship.

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Presenters

  • Lingyuan Kong

    • California Institute of Technology

Authors

  • Lingyuan Kong

    • California Institute of Technology

  • Michal Papaj

    • University of California, Berkeley

  • Hyunjin Kim

    • Caltech

  • Yiran Zhang

    • California Institute of Technology

  • Eli N Baum

    • University of California, Davis

  • Kenji Watanabe

    • National Institute for Materials Science
    • NIMS
    • Research Center for Electronic and Optical Materials, National Institute for Materials Science
    • Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • National Institute for Material Science

  • Takashi Taniguchi

    • Kyoto Univ
    • National Institute for Materials Science
    • Research Center for Materials Nanoarchitectonics
    • Research Center for Materials Nanoarchitectonics, National Institute for Materials Science
    • National Institute for Materials Sciences
    • NIMS
    • International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • National Institute for Material Science
    • International Center for Materials Nanoarchitectonics, NIMS, Japan
    • International Center for Materials Nanoarchitectonics, Tsukuba
    • National Institue for Materials Science
    • Kyoto University
    • National Institute of Materials Science
    • International Center for Materials Nanoarchitectonics and National Institute for Materials Science

  • Genda Gu

    • Brookhaven National Laboratory

  • Patrick A Lee

    • Massachusetts Institute of Technology

  • Stevan Nadj-Perge

    • Caltech