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Title: Nodeless multiband superconductivity in stoichiometric single-crystalline CaKFe 4 As 4

Measurements of the London penetration depth Δλ(T) and tunneling conductance in single crystals of the recently discovered stoichiometric iron-based superconductor CaKFe 4As 4 (CaK1144) show nodeless, two-effective-gap superconductivity with a larger gap of about 6–10 meV and a smaller gap of about 1–4 meV. Having a critical temperature T c,onset ≈ 35.8 K, this material behaves similar to slightly overdoped (Ba 1–xK x)Fe 2As 2 (e.g., x = 0.54,T c ≈ 34 K), a known multigap s ± superconductor. Here, we conclude that the superconducting behavior of stoichiometric CaK1144 demonstrates that two-gap s± superconductivity is an essential property of high-temperature superconductivity in iron-based superconductors, independent of the degree of substitutional disorder.
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [1] ;  [1] ;  [1]
  1. Ames Lab. and Iowa State Univ., Ames, IA (United States)
  2. Univ. Autonoma de Madrid, Madrid (Spain)
Publication Date:
Report Number(s):
IS-J-9232
Journal ID: ISSN 2469-9950; PRBMDO; TRN: US1700632
Grant/Contract Number:
AC02-07CH11358; 679080; GBMF4411
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 95; Journal Issue: 10; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Ames Laboratory (AMES), Ames, IA (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:
1350068
Alternate Identifier(s):
OSTI ID: 1346271