Orbital-selective correlations for topology in FeSe$_{x}$Te$_{1-x}$

TL;DR

This paper investigates how orbital-selective electronic correlations in FeSe$_{x}$Te$_{1-x}$ induce topological states near the Fermi energy, revealing a robust interplay between strong correlations and symmetry that leads to topological band features.

Contribution

It introduces a multiorbital model combined with a $U(1)$ slave spin theory to show how orbital selectivity causes band inversion and Dirac nodes in FeSe$_{x}$Te$_{1-x}$, highlighting a new mechanism for correlated topological states.

Findings

Orbital selectivity causes band inversion near the Fermi energy.

Dirac nodes are formed due to energy level renormalization.

Topological properties are robust and naturally emerge from correlations.

Abstract

Strong correlations lead to emergent excitations at low energies. When combined with symmetry constraints, they may produce topological electronic states near the Fermi energy. Within this general framework, here we address the topological features in iron-based superconductors. We examine the effects of orbital-selective correlations on the band inversion in the iron chalcogenide FeSe$_{x}$Te$_{1-x}$ near its doping of optimal superconductivity, within a multiorbital model and using a $U(1)$ slave spin theory. The orbital selectivity of the quasiparticle spectral weight, along with its counterpart of the energy level renormalization, leads to a band inversion and Dirac node formation pinned to the immediate vicinity of the Fermi energy. Our work demonstrates both the naturalness and robustness of the topological properties in FeSe$_{x}$Te$_{1-x}$, and uncovers a new setting in which strong correlations and space-group symmetry cooperate in generating strongly correlated electronic topology.