Strong Coupling Theory for Superconducting Iron Pnictides

Wei-Qiang Chen, Kai-Yu Yang, Yi Zhou, Fu-Chun Zhang
2009 Physical Review Letters  
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 inter-pocket 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 ARPES and Andreev reflection spectroscope.
doi:10.1103/physrevlett.102.047006 pmid:19257468 fatcat:z6lgymupyzcf3d7snto56k5d5e