Universal Heat Conduction in the Iron Arsenide Superconductor KFe2As2: Evidence of a d-Wave State

TitleUniversal Heat Conduction in the Iron Arsenide Superconductor KFe2As2: Evidence of a d-Wave State
Publication TypeJournal Article
Year of Publication2012
AuthorsReid JP, Tanatar MA, Juneau-Fecteau A, Gordon RT, de Cotret SR, Doiron-Leyraud N, Saito T, Fukazawa H, Kohori Y, Kihou K, Lee CH, Iyo A, Eisaki H, Prozorov R, Taillefer L
Journal TitlePhysical Review Letters
Date Published08
Type of ArticleArticle
ISBN Number0031-9007
Accession NumberWOS:000307712400010
Keywordsquasi-particle transport, thermal-conductivity, vortex state, yba2cu3o6.9

The thermal conductivity kappa of the iron arsenide superconductor KFe2As2 was measured down to 50 mK for a heat current parallel and perpendicular to the tetragonal c axis. A residual linear term at T -> 0, kappa(0)/T is observed for both current directions, confirming the presence of nodes in the superconducting gap. Our value of kappa(0)/T in the plane is equal to that reported by Dong et al. [Phys. Rev. Lett. 104, 087005 (2010)] for a sample whose residual resistivity rho(0) was 10 times larger. This independence of kappa(0)/T on impurity scattering is the signature of universal heat transport, a property of superconducting states with symmetry-imposed line nodes. This argues against an s-wave state with accidental nodes. It favors instead a d-wave state, an assignment consistent with five additional properties: the magnitude of the critical scattering rate Gamma(c) for suppressing T-c to zero; the magnitude of kappa(0)/T, and its dependence on current direction and on magnetic field; the temperature dependence of kappa(T).

URL<Go to ISI>://WOS:000307712400010
Alternate JournalPhys. Rev. Lett.