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Title: Robust s ± pairing in CaK ( Fe 1 x Ni x ) 4 As 4 ( x = 0 and 0.05) from the response to electron irradiation

Here, controlled pointlike disorder introduced by 2.5-MeV electron irradiation was used to probe the superconducting state of single crystals of CaK(Fe 1–xNi x) 4As 4 superconductor at x = 0 and 0.05 doping levels. Both compositions show an increase of the residual resistivity and a decrease of the superconducting transition temperature, T c, at the rate of dT c/dρ(T c) ≈ 0.19 K/(μΩcm) for x = 0 and 0.38 K/(μΩcm) for x = 0.05, respectively. In the Ni-doped compound (x = 0.05), the coexisting spin-vortex crystal (SVC) magnetic phase is suppressed at the rate of dT N/dρ(T N) ≈ 0.16 K/(μΩcm). The low-temperature variation of London penetration depth is well approximated by the power-law function, Δλ(T) = AT n, with n ≈ 2.5 for x = 0 and n ≈ 1.9 for x = 0.05 in the pristine state. Detailed analysis of λ(T) and T c evolution with disorder is consistent with two effective nodeless energy gaps in the density of states due to robust s± pairing. Overall the behavior of CaK(Fe 1–xNi x) 4As 4 at x = 0 is similar to a slightly overdoped Ba 1–yK yFe 2As 2 at y ≈ 0.5, and at x = 0.05more » to an underdoped composition at y ≈ 0.2.« less
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)
  2. Univ. Paris-Saclay, Palaiseau Cedex (France)
Publication Date:
Report Number(s):
IS-J-9672
Journal ID: ISSN 2469-9950; PRBMDO
Grant/Contract Number:
AC02-07CH11358; GBMF4411
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 97; Journal Issue: 14; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1439421
Alternate Identifier(s):
OSTI ID: 1434993