Constraints on the superconducting order parameter in Sr<sub>2</sub>RuO<sub>4</sub> from oxygen-17 nuclear magnetic resonance

ORAL

Abstract

The superconducting state of the quasi two-dimensional and strongly correlated perovskite Sr2RuO4 is considered to be a solid-state analogue to the superfluid 3He-A phase, with an odd-parity order parameter that breaks time-reversal symmetry. Recent experiments using in-plane uniaxial stress revealed a dramatic rise and peak of the transition temperature [1], related to a DOS enhancement [2]. Here we use 17O NMR spectroscopy to probe the nature of superconductivity in Sr2RuO4 and its evolution under uniaxial strain. A reduction of the Knight shift is observed below Tc for all strain values, consistent with a drop in spin polarization in the superconducting state [3]. In unstrained samples, our results rule out a chiral p-wave order parameter. We discuss the issue of sample heating on a sub-millisecond time scale after the NMR pulse, which is particularly relevant to superconductors with a small transition temperature (Tc ≈ 1 K).

[1] Science 355, eaaf9398 (2017)
[2] Phys. Rev. X, 9, 021044 (2019)
[3] Nature 574, 72–75 (2019)

*Alexander von Humboldt Foundation
1000 Youth Talents Plan of China
JSPS KAKENHI (JP18K04715)
JST-Mirai Program (JPMJMI18A3)
US Department of Energy (DEAC02-76SF00515)
National Science Foundation (DMR-1709304)
LDRD programme of Los Alamos National Laboratory (20170204ER)

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Presenters

  • Andrej Pustogow

    • University of California, Los Angeles

Authors

  • Andrej Pustogow

    • University of California, Los Angeles

  • Yongkang Luo

    • Huazhong University of Science and Technology
    • University of California, Los Angeles
    • Huazhong University of Science & Technology

  • Aaron Chronister

    • University of California, Los Angeles

  • Yue-Shun Su

    • University of California, Los Angeles

  • Dmitry Sokolov

    • Max Planck Institute for Chemical Physics of Solids
    • MPI CPfS, Dresden, Germany
    • Max Planck Institute for Chemical Physics of Solids, Dresden, Germany

  • Fabian Jerzembeck

    • Max Planck Institute for Chemical Physics of Solids
    • Max Planck Institute for Chemical Physics of Solids, Dresden, Germany

  • Andrew P. Mackenzie

    • Max Planck Institute for Chemical Physics of Solids
    • Max Planck Institute for Chemical Physics of Solids, Dresden, Germany

  • Clifford W. Hicks

    • Max Planck Institute for Chemical Physics of Solids
    • MPI CPfS, Dresden, Germany
    • Max Planck Institute for Chemical Physics of Solids, Dresden, Germany

  • Naoki Kikugawa

    • 5National Institute for Material Science, Japan
    • National Institute for Material Science, Tsukuba Japan
    • National Institute for Material Science, Japan
    • National Institute for Materials Science, Tsukuba, Japan

  • Srinivas Raghu

    • Institute for Materials and Energy Sciences, Stanford University
    • Stanford Univ
    • Stanford University, Stanford

  • Eric Bauer

    • Los Alamos National Laboratory
    • Los Alamos Natl Lab
    • Condensed Matter and Magnet Science Group, Los Alamos National Laboratory
    • Los Alamos National Laboratory, Los Alamos

  • Stuart Brown

    • University of California, Los Angeles