Spectroscopic Evidence for the Direct Involvement of Local Moments in the Pairing Process of the Heavy-Fermion Superconductor CeCoIn<sub>5</sub>

ORAL

Abstract

The electron pairing in heavy-fermion superconductors has been widely considered to be mediated by antiferromagnetic spin fluctuations. Nonetheless, the exact origin of the neutron spin resonance in CeCoIn5 remains controversial and the corresponding tunneling signature is missing, contrary to other unconventional superconductors including the cuprate and Fe-based superconductors. Here we report results from planar tunneling spectroscopy performed along three major crystallographic orientations of CeCoIn5 [1]. Our detailed and reproducible conductance spectra provide strong evidence for: i) the existence of preformed pairs well above Tc; and ii) the direct involvement of localized f-electron moments in the pairing process, suggesting that the local physics manifested via the Kondo resonance plays a key role. We will discuss the underlying microscopic mechanism in terms of a proposed theoretical model [2].

[1] K. Shrestha et al., submitted to PRX (2020).
[2] R. Flint et al., Nat. Phys. 4, 643 (2008); PRL 105, 246404 (2010).

*This work was supported by the NSF/DMR-1704712 (KS, SZ, LHG, WKP), DOE EFRC DE-SC0016568 (YL, RB), DOE-BES DEFG02-04-ER46105 and NSF/DMR-1206553 (KS, MBM), and was performed in part at the NHMFL funded by NSF/DMR-1644779 and the State of Florida.

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Presenters

  • Wan Kyu Park

    • Florida State University
    • National High Magnetic Field Laboratory, Florida State University

Authors

  • Keshav Shrestha

    • West Texas State Univ
    • Chemistry and Physics, West Texas A&M Univ
    • Chemistry and Physics, West Texas A&M University
    • Florida State University

  • Shengzhi Zhang

    • Florida State University
    • National High Magnetic Field Laboratory, Florida State University

  • Laura H H Greene

    • Florida State University
    • National High Magnetic Field Laboratory, Florida State University

  • You Lai

    • Florida State University

  • Ryan Baumbach

    • National High Magnetic Field Laboratory
    • Florida State University
    • National High Magnetic Field Laboratory, Florida State University
    • Physics, NHMFL, Florida State University

  • Kalyan Sasmal

    • Department of Physics, University of California, San Diego
    • University of California, San Diego

  • M Brian Maple

    • Department of Physics, University of California, San Diego
    • University of California, San Diego
    • Physics, Univ. of California, San Diego

  • Wan Kyu Park

    • Florida State University
    • National High Magnetic Field Laboratory, Florida State University