Charge-doping-induced variation of BaFe$_2$As$_2$ electronic structure and the emerging physical effects

TL;DR

This study uses DFT+DMFT to explore how charge doping affects the electronic correlations and spectral properties of BaFe$_2$As$_2$, revealing orbital-dependent correlations and the potential for orbital-selective Mott phases influencing superconductivity.

Contribution

It demonstrates the systematic variation of electronic correlation with doping and highlights the orbital-dependent nature, especially the role of the Fe-3d$_{xy}$ orbital, in the emergence of orbital-selective Mott phases.

Findings

Correlation strength varies from weak to strong with doping.

The Fe-3d$_{xy}$ orbital shows the highest correlation.

Spectral functions align with experimental observations.

Abstract

We studied the relationship between the charge doping and the correlation, and its effects on the spectral function of the BaFe$_2$As$_2$ compound in the framework of the density functional theory combined with the dynamical mean field theory (DFT+DMFT). The calculated mass enhancements showed that the electronic correlation varies systematically from weak to strong when moving from the heavily electron-doped regime to the heavily hole-doped one. Since the compound has a multi-orbital nature, the correlation is orbital-dependent and it increases as hole-doping increases. The Fe-3d$_{xy}$ (xy) orbital is much more correlated than the other orbitals, because it reaches its half-filled situation and has a narrower energy scale around the Fermi energy. Our findings can be consistently understood as the tendency of the heavily hole-doped BaFe$_2$As$_2$ compound to an orbital-selective Mott phase (OSMP). Moreover, the fact that the superconducting state of the heavily hole-doped BaFe$_2$As$_2$ is an extreme case of such a selective Mottness constrains the non-trivial role of the electronic correlation in iron-pnictide superconductors. In addition, the calculated spectral function shows a behavior that is compatible with experimental results reported for every charge-doped BaFe$_2$As$_2$ compound and clarifies the importance of the characterization of its physical effects on the material.