Intertwined charge, spin, and orbital degrees of freedom under electronic correlations in the one-dimensional Fe${}^{3+}$ chalcogenide chain

Motivated by recent developments in the study of quasi-one-dimensional iron systems with Fe${}^{2+}$, we comprehensively study the Fe${}^{3+}$ chalcogenide chain system. Based on first-principles calculations, the Fe${}^{3+}$ chain has a similar electronic structure as discussed before in the iron 2+ chain, due to similar Fe$X_4$ ($X$ = S or Se) tetrahedron chain geometry. Furthermore, a three-orbital electronic Hubbard model for this chain was constructed by using the density matrix renormalization group method. A robust antiferromagnetic coupling was unveiled in the chain direction. In addition, in the intermediate electronic correlation $U\mathrm{/}W$ region, we found an interesting orbital-selective Mott phase with the coexistence of localized and itinerant electrons ($U$ is the on-site Hubbard repulsion, while $W$ is the electronic bandwidth) {\color{blue}based on the orbital-selective behavior observed in the charge fluctuations}. Furthermore, we do not observe any obvious pairing tendency in the Fe${}^{3+}$ chain in the electronic correlation $U\mathrm{/}W$ region, where superconducting pairing tendencies were reported before in iron ladders. This suggests that superconductivity is unlikely to emerge in the Fe${}^{3+}$ systems. Our results establish with clarity the similarities and differences between Fe${}^{2+}$and Fe${}^{3+}$ iron chains, as well as iron ladders.