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arXiv · 1001.1074

Specific heat of Ba0.68K0.32Fe2As2: evidence for multiband strong-coupling superconductivity

P. Popovich·A. V. Boris·O. V. Dolgov·A. A. Golubov·D. L. Sun·C. T. Lin·R. K. Kremer·B. Keimer
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Abstract

The specific heat of high-purity $\rm Ba_{0.68}K_{0.32}Fe_2As_2$ single crystals with the highest reported superconducting $T_c$ = 38.5 K was studied. The electronic specific heat, $C_p$, below $T_c$ shows two gap features, with $Δ_1 \approx 11$ meV and $Δ_2 \approx 3.5$ meV obtained from an $α$-model analysis. The reduced gap value, $2Δ^{\rm max} / k_B T_c \approx 6.6$, the magnitude of the specific heat jump, $ΔC_p(T_c)/T_c$, and its slope below $T_c$ exhibit strong-coupling character. We also show that an Eliashberg model with two hole and two electron bands gives the correct values of $T_c$, the superconducting gaps, and the temperature dependence of the free-energy difference.

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P. Popovich, A. V. Boris, O. V. Dolgov, A. A. Golubov, D. L. Sun, C. T. Lin, R. K. Kremer, B. Keimer. 2010-05-18. Specific heat of Ba0.68K0.32Fe2As2: evidence for multiband strong-coupling superconductivity. https://arxiv.org/abs/1001.1074

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