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arXiv · 1301.5257

Evidence of d-wave Superconductivity in K_(1-x)Na_xFe_2As_2 (x = 0, 0.1) Single Crystals from Low-Temperature Specific Heat Measurements

M. Abdel-Hafiez·V. Grinenko·S. Aswartham·I. Morozov·M. Roslova·O. Vakaliuk·S. Johnston·D. V. Efremov·J. van den Brink·H. Rosner·M. Kumar·C. Hess·S. Wurmehl·A. U. B. Wolter·B. Buechner·E. L. Green·J. Wosnitza·P. Vogt·A. Reifenberger·C. Enss·R. Klingeler·M. Hempel·S. -L. Drechsler
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Abstract

From the measurement and analysis of the specific heat of high-quality K_(1-x)Na_xFe_2As_2 single crystals we establish the presence of large T^2 contributions with coefficients alpha_sc ~ 30 mJ/mol K^3 at low-T for both x=0 and 0.1. Together with the observed square root field behavior of the specific heat in the superconducting state both findings evidence d-wave superconductivity on almost all Fermi surface sheets with an average gap amplitude of Delta_0 in the range of 0.4 - 0.8 meV. The derived Delta_0 and the observed T_c agree well with the values calculated within the Eliashberg theory, adopting a spin-fluctuation mediated pairing in the intermediate coupling regime.

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M. Abdel-Hafiez, V. Grinenko, S. Aswartham, I. Morozov, M. Roslova, O. Vakaliuk, S. Johnston, D. V. Efremov, J. van den Brink, H. Rosner, M. Kumar, C. Hess, S. Wurmehl, A. U. B. Wolter, B. Buechner, E. L. Green, J. Wosnitza, P. Vogt, A. Reifenberger, C. Enss, R. Klingeler, M. Hempel, S. -L. Drechsler. 2013-01-22. Evidence of d-wave Superconductivity in K_(1-x)Na_xFe_2As_2 (x = 0, 0.1) Single Crystals from Low-Temperature Specific Heat Measurements. https://doi.org/10.1103/physrevb.87.180507

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