Abstract
Measurements of the London penetration depth and tunneling conductance in single crystals of the recently discovered stoichiometric iron-based superconductor (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 K, this material behaves similar to slightly overdoped (e.g., K), a known multigap superconductor. We conclude that the superconducting behavior of stoichiometric CaK1144 demonstrates that two-gap superconductivity is an essential property of high-temperature superconductivity in iron-based superconductors, independent of the degree of substitutional disorder.
- Received 20 June 2016
- Revised 30 November 2016
DOI:https://doi.org/10.1103/PhysRevB.95.100502
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