Magnetism and superconductivity in the two-dimensional 16-band d-p model for iron-based superconductors

The electronic states of the Fe₂As₂ plane in iron-based superconductors are investigated on the basis of the two-dimensional 16-band d-p model which includes the Coulomb interaction on a Fe site: the intra-and inter-orbital direct terms U and U′, the Hund's coupling J and the pair-transfer J′. Using the random phase approximation (RPA), we obtain the magnetic phase diagram including the stripe and the incommensurate order on the U′-J plane. We also solve the superconducting gap equation within the RPA and find that, for large J, the most favorable pairing symmetry is extended s-wave whose order parameter changes its sign between the hole pockets and the electron pockets, while it is d_xy-wave for small J.