Orbital-selective correlations and renormalized electronic structure in LiFeAs

TL;DR

This paper uses a multiorbital Hubbard model and slave spin theory to explain the large Fermi surface changes in LiFeAs through orbital-selective energy-level renormalization, highlighting local correlations' role.

Contribution

It introduces a new mechanism involving orbital selectivity for energy-level renormalization to explain electronic structure changes in LiFeAs.

Findings

Orbital selectivity causes significant Fermi surface size changes.

Local correlations can fully account for LiFeAs's electronic structure.

Universal features emerge across strongly correlated superconductors.

Abstract

Multiorbital models are important to both the correlation physics and topological behavior of quantum materials. LiFeAs is a prototype iron pnictide suitable for indepth investigation of this issue. Its electronic structure is strikingly different from the prediction of the noninteracting description. Here, a multiorbital Hubbard model for this compound is studied using a $U(1)$ slave spin theory. We demonstrate a new mechanism for a large change in the size of the Fermi surface, namely, orbital selectivity of the energy-level renormalization cooperating with its counterpart in the quasiparticle spectral weight. Using this effect, we show how the dominating features of the electronic structure in LiFeAs are understood in terms of the local correlations alone. Our results reveal a remarkable degree of universality out of the seemingly complex multiorbital building blocks across a broad range of strongly correlated superconductors.