Point Node Gap Structure of Spin-Triplet Superconductor UTe<sub>2</sub>

 · Invited

Abstract

Low-temperature electrical and thermal transport, magnetic penetration depth, and heat capacity measurements were performed on single crystals of the actinide superconductor UTe2 to determine the structure of the superconducting energy gap. Heat transport measurements performed with currents directed along both crystallographic a and b axes reveal a vanishingly small residual fermionic component of the thermal conductivity. The magnetic field dependence of the residual term follows a rapid, quasilinear increase consistent with the presence of nodal quasiparticles, rising toward the a-axis upper critical field where the Wiedemann-Franz law is recovered. Together with a quadratic temperature dependence of the magnetic penetration depth up to T/Tc = 0.3, these measurements provide evidence for an unconventional spin-triplet superconducting order parameter with point nodes. Millikelvin specific heat measurements performed on the same crystals used for thermal transport reveal an upturn below 300 mK that is well described by a divergent quantum-critical contribution to the density of states (DOS). Modeling this contribution with a T−1/3 power law allows restoration of the full entropy balance in the superconducting state and a resultant cubic power law for the electronic DOS below Tc, consistent with the point-node gap structure determined by thermal conductivity and penetration depth measurements.

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Presenters

  • Tristin Metz

    • Maryland Quantum Materials Center, Department of Physics, University of Maryland
    • Quantum Materials Center, University of Maryland, College Park
    • University of Maryland, College Park

Authors

  • Tristin Metz

    • Maryland Quantum Materials Center, Department of Physics, University of Maryland
    • Quantum Materials Center, University of Maryland, College Park
    • University of Maryland, College Park

  • Seokjin Bae

    • University of Maryland, College Park
    • Quantum Materials Center, University of Maryland, College Park

  • Sheng Ran

    • National Institute of Standards and Technology
    • NIST Center for Neutron Research, National Institute of Standards and Technology, University of Maryland, College Park
    • Quantum Materials Center, Department of Physics, University of Maryland College Park
    • Physics, Washington University in St. Louis
    • Maryland Quantum Materials Center and Department of Physics, University of Maryland, College Park
    • Department of Physics and Astronomy, University of Maryland, College Park
    • Washington University
    • Physics Department, Washington University in St. Louis
    • NIST Center for Neutron Research, National Institute of Standards and Technology
    • Washington University in St. Louis
    • Department of Physics, University of California, San Diego
    • University of Maryland, College Park

  • I-Lin Liu

    • National Institute of Standards and Technology
    • Quantum Materials Center, Department of Physics, University of Maryland College Park
    • University of Maryland, College Park
    • Quantum Materials Center, University of Maryland, College Park

  • Yun Suk Eo

    • University of Maryland, College Park
    • Maryland Quantum Materials Center and Department of Physics, University of Maryland, College Park
    • Quantum Materials Center, University of Maryland, College Park

  • Wesley T Fuhrman

    • University of Maryland, College Park
    • Maryland Quantum Materials Center and Department of Physics, University of Maryland, College Park
    • Quantum Materials Center, University of Maryland, College Park

  • Daniel Agterberg

    • University of Wisconsin - Milwaukee
    • Department of Physics, University of Wisconsin, Milwaukee

  • Steven M Anlage

    • University of Maryland, College Park
    • Physics Department, University of Maryland
    • Physics, University of Maryland, College Park
    • Quantum Materials Center, University of Maryland, College Park

  • Nicholas Butch

    • National Institute of Standards and Technology
    • NIST Center for Neutron Research, National Institute of Standards and Technology
    • Center for Neutron Research, National Institute of Standards and Technology
    • NCNR, National Institute for Standard and Technology
    • NIST/University of Maryland
    • Center of Neutron Research, National Institute of Standards and Technology, NIST
    • Center for Neutron Research, National Institute of Standards and Technology, National Institute of Standards and Technology
    • NIST Center for Neutro Research, National Institute of Standards and Technology
    • University of Maryland

  • Johnpierre Paglione

    • University of Maryland, College Park
    • Maryland Quantum Materials Center, Department of Physics, University of Maryland
    • Quantum Materials Center, Department of Physics, University of Maryland College Park
    • Quantum Materials Center, University of Maryland, College Park
    • Maryland Quantum Materials Center and Department of Physics, University of Maryland, College Park
    • University of Maryland