Specific Heat Measurements of Ba0.68K0.32Fe2As2 Single Crystals: Evidence for a Multiband Strong-Coupling Superconducting State
P. Popovich, A. V. Boris, O. V. Dolgov, A. A. Golubov, D. L. Sun, C. T. Lin, R. K. Kremer, B. Keimer
DOI 10.1103/PhysRevLett.105.027003 · Physical Review Letters
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Abstract
The specific heat of high-purity Ba0.68K0.32Fe2As2 single crystals with the highest reported superconducting Tc=38.5 K was studied. The electronic specific heat Cp below Tc shows two gap features, with Δ1≈11 meV and Δ2≈3.5 meV obtained from an α-model analysis. The reduced gap value, 2Δmax/kBTc≈6.6, the magnitude of the specific-heat jump, ΔCp(Tc)/Tc, and its slope below Tc exhibit a strong-coupling character. We also show that an Eliashberg model with two hole and two electron bands gives the correct values of Tc, the superconducting gaps, and the free-energy difference.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| Ba0.68K0.32Fe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 38.5 | Pressure not reported | onset |
| Ba0.68K0.32Fe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 38.5 | Pressure not reported | onset |
| Ba(Fe0.925Co0.075)2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| Ba1-xKxFe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 36.5 | Pressure not reported | unknown |
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