Possible Three-Dimensional Nodes in the s +/- Superconducting Gap of BaFe2(As1-xPx)(2)

We theoretically examine the superconducting state of BaFe2(As1-xPx)(2), an isovalent doping 122-iron-pnictide superconductor. We construct a three-dimensional 10-orbital model by first-principles band calculation, and investigate the superconducting gap within the spin-fluctuation-mediated pairing mechanism. The gap is basically s +/-, where the gap changes its sign between electron and hole Fermi surfaces, but three-dimensional nodal structures appear in the largely warped hole Fermi surface having a strong Z(2)/XZ/YZ orbital character. The present result, together with our previous study of the 1111 systems, explains the strong material dependence of the superconducting gap in iron pnictides.