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Nodeless multiband superconductivity in stoichiometric single-crystalline CaKFe4As4

TitleNodeless multiband superconductivity in stoichiometric single-crystalline CaKFe4As4
Publication TypeJournal Article
Year of Publication2017
AuthorsCho, K, Fente, A, Teknowijoyo, S, Tanatar, MA, Joshi, KR, Nusran, NM, Kong, T, Meier, WR, Kaluarachchi, U, Guillamon, I, Suderow, H, Bud'ko, SL, Canfield, PC, Prozorov, R
JournalPhysical Review B
Date Published03
Type of ArticleArticle
ISBN Number2469-9950
Accession NumberWOS:000396001800001
Keywordsfe-based superconductors, high-temperature superconductivity, mgb2, penetration depth, physics, scanning tunneling spectroscopy

Measurements of the London penetration depth Delta lambda(T) and tunneling conductance in single crystals of the recently discovered stoichiometric iron-based superconductor CaKFe4As4 (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,T-onset approximate to 35.8 K, this material behaves similar to slightly overdoped (Ba1-x K-x) Fe2As2 (e.g., x = 0.54, T-c approximate to 34 K), a known multigap s(+/-) superconductor. We conclude that the superconducting behavior of stoichiometric CaK1144 demonstrates that two-gap s(perpendicular to) superconductivity is an essential property of high-temperature superconductivity in iron-based superconductors, independent of the degree of substitutional disorder.

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Alternate JournalPhys. Rev. B