title: Strong coupling theory for superconducting iron pnictides.
abstract: Superconductivity in iron pnictides is studied by using a two-orbital Hubbard model in the large U limit. The Coulomb repulsion induces an orbital-dependent pairing between charge carriers. The pairing is found mainly from the scattering within the same Fermi pocket. The interpocket pair scatterings determine the symmetry of the superconductivity, which is extended s wave at small Hund's coupling, and d wave at large Hund's coupling and large U. The former is consistent with recent experiments of angle-resolved photoemission spectroscopy and Andreev reflection spectroscopy.
authors.affiliation: Department of Physics, the University of Hong Kong, Hong Kong, China.
authors.forename: Wei-Qiang
authors.initials: WQ
authors.lastname: Chen
authors.forename: Kai-Yu
authors.initials: KY
authors.lastname: Yang
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhou
authors.forename: Fu-Chun
authors.initials: FC
authors.lastname: Zhang