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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

Journal Article · · Physical Review B
 [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)

Here, controlled pointlike disorder introduced by 2.5-MeV electron irradiation was used to probe the superconducting state of single crystals of CaK(Fe1–xNix)4As4 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, Tc, at the rate of dTc/dρ(Tc) ≈ 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 dTN/dρ(TN) ≈ 0.16 K/(μΩcm). The low-temperature variation of London penetration depth is well approximated by the power-law function, Δλ(T) = ATn, 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 Tc 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(Fe1–xNix)4As4 at x = 0 is similar to a slightly overdoped Ba1–yKyFe2As2 at y ≈ 0.5, and at x = 0.05 to an underdoped composition at y ≈ 0.2.

Research Organization:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
AC02-07CH11358
OSTI ID:
1439421
Report Number(s):
IS-J--9672
Journal Information:
Physical Review B, Journal Name: Physical Review B Journal Issue: 14 Vol. 97; ISSN 2469-9950; ISSN PRBMDO
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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Observation of two collapsed phases in CaRbF e 4 A s 4 journal July 2019
Anisotropic upper critical field of pristine and proton-irradiated single crystals of the magnetically ordered superconductor RbEuFe 4 As 4 journal August 2019
Analysis of the London penetration depth in Ni-doped CaKFe 4 As 4 journal September 2019
Antiferromagnetic order in CaK ( Fe 1 − x Ni x ) 4 As 4 and its interplay with superconductivity journal June 2018
Anisotropic superconductivity and magnetism in single-crystal RbEuFe 4 As 4 journal September 2018