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

TL;DR

This study uses first-principles calculations and the density matrix renormalization group to analyze the electronic, magnetic, and orbital properties of Fe$^{3+}$ chalcogenide chains, revealing an orbital-selective Mott phase and the unlikelihood of superconductivity.

Contribution

It provides a comprehensive comparison of Fe$^{3+}$ and Fe$^{2+}$ chains, introducing an orbital-selective Mott phase in Fe$^{3+}$ systems and assessing their potential for superconductivity.

Findings

Identified a robust antiferromagnetic coupling along the chain.

Discovered an orbital-selective Mott phase with coexisting localized and itinerant electrons.

Found no evidence of superconducting pairing tendencies in Fe$^{3+}$ chains.

Abstract

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 $U/W$ 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 $U/W$ 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.