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Title: Anisotropy and multiband superconductivity in Sr 2 RuO 4 determined by small-angle neutron scattering studies of the vortex lattice [Anisotropy and multiband superconductivity in Sr 2 RuO 4 ]

Despite numerous studies the exact nature of the order parameter in superconducting Sr 2RuO 4 remains unresolved. We have extended previous small-angle neutron scattering studies of the vortex lattice in this material to a wider field range, higher temperatures, and with the field applied close to both the <100> and <110> basal plane directions. Measurements at high field were made possible by the use of both spin polarization and analysis to improve the signal-to-noise ratio. Rotating the field towards the basal plane causes a distortion of the square vortex lattice observed for H // <001> and also a symmetry change to a distorted triangular symmetry for fields close to <100>.The vortex lattice distortion allows us to determine the intrinsic superconducting anisotropy between the c axis and the Ru-O basal plane, yielding a value of ~60 at low temperature and low to intermediate fields. This greatly exceeds the upper critical field anisotropy of ~20 at low temperature, reminiscent of Pauli limiting. Indirect evidence for Pauli paramagnetic effects on the unpaired quasiparticles in the vortex cores are observed, but a direct detection lies below the measurement sensitivity. The superconducting anisotropy is found to be independent of temperature but increases for fields >more » 1 T, indicating multiband superconductvity in Sr 2RuO 4. Lastly, the temperature dependence of the scattered intensity provides further support for gap nodes or deep minima in the superconducting gap.« less
Authors:
 [1] ;  [2] ;  [2] ;  [2] ;  [3] ;  [4] ;  [5] ;  [4] ;  [6] ;  [7] ; ORCiD logo [2]
  1. Univ. of Notre Dame, Notre Dame, IN (United States); Duke Univ., Durham, NC (United States)
  2. Univ. of Notre Dame, Notre Dame, IN (United States)
  3. Northwestern Univ., Evanston, IL (United States); Texas A & M Univ., College Station, TX (United States)
  4. Kyoto Univ., Kyoto (Japan)
  5. Kyoto Univ., Kyoto (Japan); Fudan Univ., Shanghai (China)
  6. Institut Laue-Langevin, Grenoble (France)
  7. Paul Scherrer Inst. (PSI), Villigen (Switzerland)
Publication Date:
Grant/Contract Number:
SC0005051
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 96; Journal Issue: 17; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Univ. of Notre Dame, Notre Dame, IN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1408758
Alternate Identifier(s):
OSTI ID: 1408791