Time-reversal symmetry-breaking superconductivity in FeSe<sub>1-x</sub>S<sub>x</sub>

ORAL

Abstract

The FeSe1-xSx superconductors involving non-magnetic nematic phase and its quantum criticality provide a unique platform to investigate the relationship between nematicity and superconductivity. The lifting of superconducting gap nodes due to twin boundaries has been observed experimentally, which suggests indirect evidence for time reversal symmetry breaking (TRSB). It is consistent with the theoretical prediction that the superconducting order parameter breaks the time-reversal symmetry near the nematic twin boundaries. We have performed the muon spin rotation (μSR) measurements on FeSe and observed the spontaneous internal field below the superconducting transition temperature Tc, providing evidence for TRSB state in FeSe. Here we extend zero-field μSR studies to tetragonal FeSe1-xSx (x=0.18, 0.2) without nematicity. We find that the μSR relaxation rate starts to grow below Tc in these crystals. This indicates that weak but finite internal magnetic field is induced in the superconducting state, providing strong evidence for TRSB state not only near twin boundaries but also inside the bulk of FeSe1-xSx.

*Supported by a Grant-in-Aid for Scientific Research on Innovative Areas “Quantum Liquid Crystals” (KAKENHI Grant No. JP19H05824) from Japan Society for the Promotion of Science.

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Presenters

  • Mingwei Qiu

    • Univ of Tokyo
    • Department of Advanced Materials Science, University of Tokyo
    • Department of Advanced Materials Science, The University of Tokyo

Authors

  • Mingwei Qiu

    • Univ of Tokyo
    • Department of Advanced Materials Science, University of Tokyo
    • Department of Advanced Materials Science, The University of Tokyo

  • Kohei Matsuura

    • Univ of Tokyo
    • Department of Advanced Materials Science, University of Tokyo
    • Department of Advanced Materials Science, The University of Tokyo
    • Univ of Tokyo-Kashiwanoha

  • Takaaki Takenaka

    • Univ of Tokyo
    • Department of Advanced Material Science, University of Tokyo

  • Yuichi Sugimura

    • Univ of Tokyo
    • Department of Advanced Materials Science, University of Tokyo

  • Takasada Shibauchi

    • Advanced Materials Science, University of Tokyo
    • Univ of Tokyo-Kashiwanoha
    • Department of Advanced Materials Science, University of Tokyo
    • Univ of Tokyo
    • Dept. Adv. Mat. Sci., Univ. Tokyo
    • Univ. of Tokyo
    • Department of Advanced Materials Science, The University of Tokyo
    • Department of Advanced Material Science, University of Tokyo

  • Qi Sheng

    • Columbia University
    • Department of Physics, Columbia University

  • Kohtaro Yamakawa

    • Department of Physics, Columbia University

  • Yasutomo J Uemura

    • Colombia University
    • Department of Physics, Columbia University

  • Yipeng Cai

    • Stewart Blusson Quantum Matter Institute, University of British Columbia
    • McMaster University

  • Andrea Damascelli

    • University of British Columbia
    • Stewart Blusson Quantum Matter Institute, University of British Columbia

  • Ryan P Day

    • University of British Columbia
    • Stewart Blusson Quantum Matter Institute, University of British Columbia

  • Kenji Kojima

    • Stewart Blusson Quantum Matter Institute, University of British Columbia

  • James W Beare

    • McMaster Univ
    • Department of Physics & Astronomy, McMaster University
    • McMaster University

  • Graeme Luke

    • McMaster Univ
    • Physics and Astronomy, McMaster University
    • Department of Physics & Astronomy, McMaster University
    • McMaster University

  • Zhao Guo Qiang

    • Institute of Physics, Chinese Academy of Sciences

  • Changqing Jin

    • Chinese Academy of Sciences
    • EX5, Institute of Physics, Chinese Academy of Sciences
    • Institute of Physics, Chinese Academy of Sciences

  • Yilun Gu

    • Department of Physics, Zhejiang University

  • LiCheng Fu

    • Department of Physics, Zhejiang University

  • Fanlong Ning

    • Department of Physics, Zhejiang University

  • Mikihiko Saito

    • Univ of Tokyo
    • Department of Advanced Materials Science, University of Tokyo