Electron correlation induced small anisotropy in iron-based superconductors

We have investigated the electron correlation effect on the electronic structures and transport properties of the iron-based superconductors using the density functional theory (DFT) and dynamical mean field theory (DMFT). By considering the Fe 3d electron correlation using the DMFT, the bandwidth near the Fermi level is substantially suppressed compared to the conventional DFT calculation. Because of the different renormalization factors of each 3d orbital, the DMFT gives considerably reduced electrical anisotropy compared to the DFT results, which explains the unusually small anisotropic resistivity and superconducting property observed in the iron-based superconductors. We suggest that the electron correlation effect should be considered to explain the anisotropic transport properties of the general d/f valence electron system.