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

作者：Reid J Ph^*; Tanatar M A; Juneau Fecteau A; Gordon R T; de Cotret S Rene; Doiron Leyraud N; Saito T; Fukazawa H; Kohori Y; Kihou K; Lee C H; Iyo A; Eisaki H; Prozorov R; Taillefer Louis

来源：Physical Review Letters, 2012, 109(8): 087001.

DOI：10.1103/PhysRevLett.109.087001

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 -%26gt; 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 o

• 出版日期2012-8-21