Specific Heat Measurements of Ba 0.68 K 0.32 Fe 2 As 2 Single Crystals: Evidence for a Multiband Strong-Coupling Superconducting State
2010; American Physical Society; Volume: 105; Issue: 2 Linguagem: Inglês
10.1103/physrevlett.105.027003
ISSN1092-0145
AutoresP. Popovich, A. V. Boris, O. V. Dolgov, A. A. Golubov, Dunlu Sun, C. T. Lin, Reinhard K. Kremer, B. Keimer,
Tópico(s)Physics of Superconductivity and Magnetism
ResumoThe specific heat of high-purity Ba(0.68)K(0.32)Fe2As2 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, 2Δ(max)/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.
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