Evidence of d-wave superconductivity in K1−xNaxFe2As2 (x = 0,0.1) single crystals from low-temperature specific-heat measurements

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

doi:10.1103/PhysRevB.87.180507

Evidence of d-wave superconductivity in K_1−xNa_xFe₂As₂ (x = 0,0.1) single crystals from low-temperature specific-heat measurements

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

From the measurement and analysis of the specific heat of high-quality K_1−xNa_xFe₂As₂ single crystals we establish the presence of large T² contributions with coefficients α_sc ≈ 30 mJ/mol K³ at low T for both x = 0 and x = 0.1. Together with the observed √B behavior of the specific heat in the superconducting state both findings give evidence of d-wave superconductivity on almost all Fermi-surface sheets with an average gap amplitude of Δ₀ in the range of 0.4–0.8 meV. The derived 0 and observed T_c agree well with the values calculated within Eliashberg theory, adopting a spin-fluctuation mediated pairing in the intermediate coupling regime.

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High Magnetic Field Laboratory (HLD)

Physical Review B 87(2013), 180507(R)
DOI: 10.1103/PhysRevB.87.180507
Cited 37 times in Scopus

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