Charge-doping-induced variation of the superconducting BaFe2As2 electronic structure and the emerging physical effects: a DFT plus DMFT study

We performed a first-principles study in the framework of density functional theory combined with dynamical mean-field theory (DFT+DMFT) on the relationship between the charge doping and the correlations in BaFe2As2 and investigated how the relationship can affect its spectral function. Structural positions were systematically optimized for a wide range of electron and hole dopings in BaFe2-xCoxAs2 (0 <= x <= 0.7) and Ba1-xKxFe2As2 (0 <= x <= 1), respectively, and the found physical characteristics are well compatible with the existing experimental results. Our results could clarify both the importance of structural parameters in iron-based superconductors and the capability of DFT+DMFT in predicting them. The calculated mass enhancements showed that the strength of the electronic correlations varies systematically from weak to strong when moving from the heavily electron-doped regime to the heavily hole-doped one. Since the BaFe2As2 compound has a multi-orbital nature, its correlations are orbital-dependent and increase as hole-doping increases. The Fe-3d(xy) (xy) orbital is much more correlated than the others because it has reached its half-filled situation and has a narrower energy range around the Fermi level. Our findings can be consistently understood as the tendency of the heavily hole-doped BaFe2As2 compound to the orbital-selective Mott phase. Furthermore, the fact that the superconducting state of the heavily hole-doped BaFe2As2 is an extreme case of such a selective Mottness constrains the non-trivial role of the electronic correlations in iron-pnictide superconductors. The results are consistent with the previous theoretical and experimental literature. In particular, the calculated spectral function is compatible with the existing experimental results on every charge-doped BaFe2As2 compound.

Automated summary

The study investigated the relationship between charge doping and correlations in BaFe2As2 using DFT+DMFT, showing that electronic correlations strengthen systematically from electron-doping to hole-doping regimes. Due to its multi-orbital nature, correlations in BaFe2As2 are orbital-dependent, with the Fe-3d(xy) orbital exhibiting the most correlation.