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Spectroscopic evidence for pre-formed heavy electron pairs and novel pairing mechanism in CeCoIn<sub>5</sub> (Part 2/2)

ORAL

Abstract

The glue that binds heavy electrons into pairs in CeCoIn5(Tc=2.3K) is not known unambiguously yet. The origin of the neutron resonance peak[1] is still controversial[2] despite the original interpretation as evidence for the spin fluctuation mechanism. Also, the hump-dip feature expected in tunneling conductance is missing in scanning tunneling spectroscopy measurements[3]. Here, we present results from planar tunneling spectroscopy on CeCoIn5, revealing the pairing gap opens at Tp~5K. Interestingly, under a magnetic field, the pairing gap turns into a field-induced gap-like feature (FIG). The FIG increases linearly with the field and is observed only below Tp. This concomitance of the FIG with the pairing along with its linear field dependence strongly suggests that it is intimately tied to the underlying pairing mechanism. We will discuss these findings in the context of the composite pairing mechanism based on the cooperative two-channel Kondo effect[4].

[1]Stock,et al,PRL100,087001(2008).
[2]Song,et al,Nat.Comm.7,12774(2016).
[3]Fasano,et al,Physica B536,798(2018);Allan,et al,Nat.Phys.9,468(2013).
[4]Flint,et al,Nat.Phys.4,643(2008)

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Presenters

  • Laura Greene

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

Authors

  • Keshav Shrestha

    Natl High Magnetic Field Lab, National High Magnetic Field Laboratory, Idaho National Laboratory

  • Shengzhi Zhang

    Florida State University, National High Magnetic Field Lab, Florida State University

  • Laura Greene

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

  • Joe D Thompson

    Los Alamos National Laboratory, Los Alamos Natl Lab

  • You Lai

    Florida State University, Los Alamos National Laboratory, Florida State Univ

  • Ryan Baumbach

    National High Magnetic Field Laboratory/Florida State University, MagLab Tallahassee, National High Magnetic Field Laboratory, National High Magnetic Field Lab, Florida State University, Florida State Univ, Natl High Magnetic Field Lab, 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, Physics, University of California, San Diego

  • M Brian Maple

    Department of Physics, University of California, San Diego, UCSD, University of California, San Diego, physics, University of Califormia, San Diego, Departement of Physics, University fo California, San Diego, Physics, University of California, San Diego

  • Wan Kyu Park

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