Pairing mechanism and symmetry of iron-based high-temperature superconductivity

用动力学平均场理论和Eliashberg方程研究了铁基超导体中的强关联效应。在最近的ARPES实验中，重整化因子表现出明显的轨道依赖性。与RPA相比，由于局域关联效应，磁序和轨道序受到很大程度的抑制。值得注意的是，由于轨道涨落引起的S+-配对相相对于RPA结果有很大的扩展，而由于磁涨落引起的S+-配对相则减少了。还研究了Fed和Asp电子间库仑相互作用的影响，发现这是导致C66弹性软化的铁轨道(FO)涨落的增强。由于Q空间的分离，在位d-d库仑相互作用引起的FO涨落和反铁磁涨落共同提高了S+波超导的T_c，没有任何竞争。

Strong correlation effects in iron-based superconductors have been investigated by using the dynamical mean-field theory with the Eliashberg equation. The renormalization factor exhibits significant orbital dependence as observed in recent ARPES experiments. The magnetic and orbital orders are largely suppressed as compared with those from the RPA due to local correlation effects. Remarkably, the s++-pairing phase due to the orbital fluctuation is largely expanded relative to the RPA result, while the s+--pairing phase due to the magnetic fluctuation is reduced. The effect of the intersite Coulomb interaction between Fe d and As p electrons has also been studied and is found to enhance the ferro-orbital (FO) fluctuation responsible for the C66 elastic softening. The FO fluctuation and the antiferromagnetic fluctuation enhanced due to the onsite d-d Coulomb interaction cooperatively enhance Tc of s+--wave superconductivity without any competition by virtue of the q-space segregation.