The five-orbital Hubbard model for iron-based superconductors is investigated using the dynamical mean-field theory combined with the Eliashberg equation to clarify the local correlation effects on the electronic states and the superconductivity. In the specific case where the antiferromagnetic (AFM) and antiferro-orbital (AFO) fluctuations are comparably enhanced, the orbital dependence of the vertex function is significantly large, while that of the self-energy is small, in contrast to the AFM fluctuation-dominated case where the vertex function (the self-energy) shows a small (large) orbital dependence. The orbital-dependent vertex function together with the nesting between the inner and outer hole Fermi surfaces results in the enhancement of the inter-orbital ferromagnetic (FM) fluctuation in addition to the AFM and AFO fluctuations. In this case, the hole-s±-wave pairing with the sign change of the two hole Fermi surfaces is mediated by the coexisting three fluctuations as expected to be observed in the specific compound LiFeAs.
ASJC Scopus subject areas
- Physics and Astronomy(all)