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 (Tc=1.6K) 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 quasi-linear increase consistent with the presence of nodal quasiparticles, rising rapidly toward the a-axis upper critical field where the Wiedemann-Franz (WF) 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 positioned along the crystallographic a-axis. Millikelvin specific heat measurements 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 reveals a perfect T3 power law for the electronic DOS below Tc which is consistent with the point nodal gap structure determined by thermal conductivity and penetration depth measurements.

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Presenters

  • Tristin Metz

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

Authors

  • Tristin Metz

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

  • Seokjin Bae

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

  • Sheng Ran

    • NIST Center for Neutron Research, National Institute of Standards and Technology
    • University of Maryland, College Park
    • National Institute of Standards and Technology
    • Physics Department, University of Maryland
    • University of Maryland
    • University of Maryland, College Park & NIST
    • Department of Physics, University of Maryland, College Park
    • NIST Center for Neutron Research

  • I-Lin Liu

    • Physics Department, University of Maryland
    • Department of Physics, University of Maryland, College Park
    • University of Maryland, College Park
    • NIST Center for Neutron Research

  • Yun Suk Eo

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

  • Wesley T Fuhrman

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

  • Daniel Agterberg

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

  • Steven Anlage

    • University of Maryland, College Park
    • Department of Physics and Department of Electrical and Computer Engineering, University of Maryland, College Park
    • Physics Department, University of Maryland, College Park
    • Center for Quantum Materials, University of Maryland

  • Nicholas Butch

    • NIST Center for Neutron Research, National Institute of Standards and Technology
    • National Institute of Standards and Technology
    • Center of Neutron Research, National Institute of Standards and Technology
    • Center for Neutron Research, National Institute of Standards and Technology
    • NIST Center for Neutron Research
    • NIST center for neutron research
    • NIST
    • NIST Center for Neutron Research, National Institute of Standards and Technology,
    • University of Maryland, College Park & NIST
    • National Institute of Standards and Technology Center for Neutron Research

  • Johnpierre Paglione

    • University of Maryland, College Park
    • Physics Department, University of Maryland
    • Maryland Quantum Materials Center, Department of Physics, University of Maryland College Park
    • Department of Physics, University of Maryland, College Park
    • University of Maryland, College Park & NIST
    • Univ of Maryland-Colege Park
    • Center for Quantum Materials, University of Maryland
    • Maryland Quantum Materials Center, Department of Physics, University of Maryland-College Park,College Park, Maryland 20742