Hund bands in spectra of multiorbital systems

TL;DR

This paper reveals the existence of Hund bands in the spectra of multiorbital systems, which are distinct features at energies determined solely by Hund coupling, providing new insights into strongly correlated materials.

Contribution

It demonstrates the presence of Hund bands at energies set by Hund coupling in multiorbital Hubbard models, using advanced numerical methods and dynamical mean-field theory.

Findings

Hund bands occur at energies given by Hund coupling J_H

Spectral features are distinct from Hubbard satellites

Results are validated across different models and methods

Abstract

Spectroscopy experiments are routinely used to characterize the behavior of strongly correlated systems. An in-depth understanding of the different spectral features is thus essential. Here, we show that the spectrum of the multiorbital Hubbard model exhibits unique Hund \ms{bands} that occur at energies given only by the Hund coupling $J_\mathrm{H}$, as distinct from the Hubbard satellites following the interaction $U$. We focus on experimentally relevant single-particle and optical spectra that we calculate for a model related to iron chalcogenide ladders. The calculations are performed via the density-matrix renormalization group and Lanczos methods. The generality of the implications is verified by considering a generic multiorbital model within dynamical mean-field theory.