Signatures of Mottness and Hundness in archetypal correlated metals

TL;DR

This paper investigates how Mott and Hund physics influence the electronic properties of multi-orbital materials, identifying key energy scales and signatures that distinguish these two types of strong correlations.

Contribution

It introduces a framework of four energy scales to differentiate Mott and Hund physics in correlated metals, supported by realistic material studies and model analysis.

Findings

Identification of four characteristic energy scales for screening processes.

Distinct temperature-dependent signatures for Mott versus Hund physics.

Validation of concepts through both material-specific and model Hamiltonian studies.

Abstract

Physical properties of multi-orbital materials depend not only on the strength of the effective interactions among the valence electrons but also on their type. Strong correlations are caused by either Mott physics that captures the Coulomb repulsion among charges, or Hund physics that aligns the spins in different orbitals. We identify four energy scales marking the onset and the completion of screening in orbital and spin channels. The differences in these scales, which are manifest in the temperature dependence of the local spectrum and of the charge, spin and orbital susceptibilities, provide clear signatures distinguishing Mott and Hund physics. We illustrate these concepts with realistic studies of two archetypal strongly correlated materials, and corroborate the generality of our conclusions with a model Hamiltonian study.