Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 34: SC: Iron-Based Superconductors - 122

TT 34.9: Vortrag

Donnerstag, 25. März 2010, 16:15–16:30, H20

Calorimetric studies of hole-doped Ba_0.68K_0.32Fe₂As₂ multiband superconductor — •P. Popovich, A. V. Boris, O. V. Dolgov, D. L. Sun, C. T Lin, R. K. Kremer, and B. Keimer — Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany

We report on the determination of the low temperature specific heat of hole-doped Ba_0.68K_0.32Fe₂As₂ single crystals with a sharp ( < 0.6 K) anomaly at T_c ≈ 38.5 K. The jump at T_c is ΔC/T ≈ 120 mJ/molK². The low residual electronic specific heat ( < 2 mJ/molK²) shows that the amount of the non-superconducting impurities in our single-phase samples is less than 3%. In order to investigate the electronic part of the specific heat we subtracted a phonon background. As a background we used either our experimental specific heat data on a non-superconducting non-magnetic isostructural substance or a set of Einstein modes. Both models give qualitatively the same result. The α-model with two superconducting gaps fits well to the SC-induced electronic specific heat. Our findings imply that the superconducting properties of Ba_0.68K_0.32Fe₂As₂ can be well described in a framework of the strong-coupling model.