paper

Line nodes in the energy gap of high-temperature superconducting BaFe_2(As_{1-x}P_x)_2 from penetration depth and thermal conductivity measurements

arXiv:0907.4399 · doi:10.1103/PhysRevB.81.220501

Abstract

We report magnetic penetration depth and thermal conductivity data for high-quality single crystals of BaFe $_{2}$ (As $_{1 - x}$ P $_{x}$ ) $_{2}$ ( $T_{c} = 30$ \,K) which provide strong evidence that this material has line nodes in its energy gap. This is distinctly different from the nodeless gap found for (Ba,K)Fe $_{2}$ As $_{2}$ which has similar $T_{c}$ and phase diagram. Our results indicate that repulsive electronic interactions play an essential role for Fe-based high- $T_{c}$ superconductivity but that uniquely there are distinctly different pairing states, with and without nodes, which have comparable $T_{c}$ .

4 pages, 3 figures, revised version to be published in Phys. Rev. B Rapid Communication