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arXiv · 0812.2069

Full Gap Superconductivity in Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ Probed by Muon Spin Rotation

M. Hiraishi·R. Kadono·S. Takeshita·M. Miyazaki·A. Koda·H. Okabe·J. Akimitsu
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Abstract

Superfluid density ($n_s$) in the mixed state of an iron pnictide superconductor Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ is determined by muon spin rotation for a sample with optimal doping ($x=0.4$). The temperature dependence of $n_s$ is perfectly reproduced by the conventional BCS model for s-wave paring, where the order parameter can be either a single-gap with $Δ=8.35(6)$ meV [$2Δ/k_BT_c=5.09(4)$], or double-gap structure with $Δ_1=12$ meV (fixed) [$2Δ_1/k_BT_c=7.3$] and $Δ_2=6.8(3)$ meV [$2Δ_2/k_BT_c=4.1(2)$]. The latter is consistent with the recent result of angle-resolved photo-emssion spectroscopy. The large gap parameters ($2Δ/k_BT_c$) indicate extremely strong coupling of carriers to bosons that mediate the Cooper pairing.

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M. Hiraishi, R. Kadono, S. Takeshita, M. Miyazaki, A. Koda, H. Okabe, J. Akimitsu. 2008-12-18. Full Gap Superconductivity in Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ Probed by Muon Spin Rotation. https://doi.org/10.1143/jpsj.78.023710

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