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Title: Point-node gap structure of the spin-triplet superconductor UTe 2

Journal Article · · Physical Review B
 [1]; ORCiD logo [1];  [2];  [2];  [1];  [1];  [3]; ORCiD logo [1];  [2]; ORCiD logo [4]
  1. Univ. of Maryland, College Park, MD (United States)
  2. Univ. of Maryland, College Park, MD (United States); National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). Center for Neutron Research
  3. Univ. of Wisconsin, Milwaukee, WI (United States)
  4. Univ. of Maryland, College Park, MD (United States); Canadian Inst. for Advanced Research, Toronto, ON (Canada)

In this work, low-temperature electrical and thermal transport, magnetic penetration depth, and heat capacity measurements were performed on single crystals of the actinide superconductor UTe 2 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 / T c = 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 T c , consistent with the point-node gap structure determined by thermal conductivity and penetration depth measurements.

Research Organization:
Univ. of Maryland, College Park, MD (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; USDOE Office of Science (SC), High Energy Physics (HEP); US Air Force Office of Scientific Research (AFOSR); National Science Foundation (NSF); Gordon and Betty Moore Foundation
Grant/Contract Number:
SC0018788; SC0019154; SC0017931; FA9550-14-1-0332; DMR-1410712; GBMF4419
OSTI ID:
1604581
Journal Information:
Physical Review B, Vol. 100, Issue 22; ISSN 2469-9950
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 62 works
Citation information provided by
Web of Science

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Cited By (3)

Experimental consequences of Bogoliubov Fermi surfaces journal January 2020
Chiral superconductivity in heavy-fermion metal UTe2 journal March 2020
Experimental consequences of Bogoliubov Fermi surfaces text January 2019