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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