Effects of electron irradiation on resistivity and London penetration depth of Ba1-xKxFe2As2 (x <= 0.34) iron-pnictide superconductor

Journal Article · Mon Sep 01 04:00:00 EDT 2014 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.90.104514· OSTI ID:1166894

Cho, K ^[1]; Konczykowski, M ^[2]; Murphy, Jason ^[1]; Kim, H ^[1]; Tanatar, Makariy A ^[1]; Straszheim, Warren E ^[1]; Shen, B ^[3]; Wen, H H ^[3]; Prozorov, Ruslan ^[1]

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1. Ames Laboratory
2. Laboratoire des Solides Irradies
3. Nanjing University

Irradiation with 2.5 MeV electrons at doses up to 5.2×1019 electrons/cm2 was used to introduce pointlike defects in single crystals of Ba1-xKxFe2As2 with x=0.19 (Tc=14K),0.26 (Tc=32K), 0.32 (Tc=37K), and 0.34 (Tc=39K) to study the superconducting gap structure by probing the effect of nonmagnetic scattering on electrical resistivity ρ(T) and London penetration depth λ(T). For all compositions, the irradiation suppressed the superconducting transition temperature Tc and increased resistivity. The low-temperature behavior of λ(T) is best described by the power-law function, Δλ(T)=A(T/Tc)n. While substantial suppression of Tc supports s± pairing, in samples close to the optimal doping, x=0.26, 0.32, and 0.34, the exponent n remained high (n≥3), indicating almost exponential attenuation and thus a robust full superconducting gap. For the x=0.19 composition, which exhibits coexistence of superconductivity and long-range magnetism, the suppression of Tc was much more rapid, and the exponent n decreased toward the s± dirty limit of n=2. In this sample, the irradiation also suppressed the temperature of structural/magnetic transition Tsm from 103 to 98 K, consistent with the itinerant nature of the long-range magnetic order. Our results suggest that underdoped compositions, especially in the coexisting regime, are most susceptible to nonmagnetic scattering and imply that in multiband Ba1-xKxFe2As2 superconductors, the ratio of the interband to intraband pairing strength, as well as the related gap anisotropy, increases upon the departure from the optimal doping.

• Research Organization: Ames Laboratory (AMES), Ames, IA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC02-07CH11358
• OSTI ID: 1166894
• Report Number(s): IS-J 8480; ArticleNumber: 104514
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 10 Vol. 90; ISSN 1098-0121; ISSN PRBMDO
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

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36 MATERIALS SCIENCE