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Title: Direct evidence for a pressure-induced nodal superconducting gap in the Ba0.65Rb0.35Fe2As2 superconductor

The superconducting gap structure in iron-based high-temperature superconductors (Fe-HTSs) is non-universal. Contrasting with other unconventional superconductors, in the Fe-HTSs both d-wave and extended s-wave pairing symmetries are close in energy. Probing the proximity between these very different superconducting states and identifying experimental parameters that can tune them is of central interest. Here we report high-pressure muon spin rotation experiments on the temperature-dependent magnetic penetration depth in the optimally doped nodeless s-wave Fe-HTS Ba0.65Rb0.35Fe2As2. Upon pressure, a strong decrease of the penetration depth in the zero-temperature limit is observed, while the superconducting transition temperature remains nearly constant. More importantly, the low-temperature behaviour of the inverse-squared magnetic penetration depth, which is a direct measure of the superfluid density, changes qualitatively from an exponential saturation at zero pressure to a linear-in-temperature behaviour at higher pressures, indicating that hydrostatic pressure promotes the appearance of nodes in the superconducting gap.
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [3] ;  [4] ;  [5] ;  [6] ;  [4] ;  [1] ;  [2] ;  [1]
  1. Paul Scherrer Inst. (PSI), Villigen (Switzerland)
  2. Univ. of Minnesota, Minneapolis, MN (United States)
  3. Leibniz Inst. for Solid State and Materials Research (IFW), Dresden (Germany)
  4. Univ. of Zurich (Switzerland)
  5. Polish Academy of Sciences (PAS), Wroclaw (Poland). Inst. of Low Temperature and Structure Research
  6. Tbilisi State Univ., Tbilisi (Georgia)
Publication Date:
OSTI Identifier:
1239551
Grant/Contract Number:
SC0012336
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 6; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Paul Scherrer Inst. (PSI), Villigen (Switzerland)
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