Two-Gap Superconductivity in CaFe_{0.88}Co_{0.12}AsF Revealed by Temperature Dependence of the Lower Critical Field H_{c1}^c(T)
arXiv:1907.04033 · doi:10.1038/s41535-019-0173-0
Abstract
Gap symmetry and structure are crucial issues in understanding the superconducting mechanism of unconventional superconductors. Here we report an in-depth investigation on the out-of-plane lower critical field of fluorine-based 1111 system superconductor CaFeCoAsF with = 21 K. A pronounced two-gap feature is revealed by the kink in the temperature dependent curve. The magnitudes of the two gaps are determined to be = 0.86 meV and = 4.48 meV, which account for 74% and 26% of the total superfluid density respectively. Our results suggest that the local antiferromagnetic exchange pairing picture is favored compared to the Fermi surface nesting scenario.
arXiv comment19 pages, 4 figures
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