Robust $s_{\pm }$ pairing in $\mathrm{CaK}{\left({\mathrm{Fe}}_{1–x}{\mathrm{Ni}}_x\right)}_4{\mathrm{As}}_4$ ( $x=0$ and 0.05) from the response to electron irradiation

Journal Article · 27 April 2018 · Physical Review B

DOI: https://doi.org/10.1103/PhysRevB.97.140508 · OSTI ID:1439421

Teknowijoyo, S. ^[1]; Cho, K. ^[1]; Konczykowski, M. ^[2]; Timmons, E. I. ^[1]; Tanatar, M. A. ^[1]; Meier, W. R. ^[1]; Xu, M. ^[1]; Bud'ko, S. L. ^[1]; Canfield, P. C. ^[1]; Prozorov, R. ^[1]

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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(Fe_1–xNi_x)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, 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) = 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 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)₄As₄ at x = 0 is similar to a slightly overdoped Ba_1–yK_yFe₂As₂ 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; GBMF4411
• OSTI ID: 1439421
• Alternate ID(s): OSTI ID: 1434993
• Report Number(s): IS-J-9672; PRBMDO; TRN: US1900606
• Journal Information: Physical Review B, Vol. 97, Issue 14; ISSN 2469-9950
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English