Hund's metallicity enhanced by van Hove singularity in cubic perovskite systems

TL;DR

This study demonstrates that van Hove singularities significantly enhance Hund's metallicity in cubic perovskite systems, revealing a synergistic effect between electronic structure features and Hund's coupling.

Contribution

The paper provides a systematic analysis of how van Hove singularities amplify Hund's metallicity using a simplified model and dynamical mean-field theory.

Findings

VHS substantially enhances Hund's metallicity.

A range of parameters shows synergy between VHS and Hund's coupling.

Quantitative estimates of metallicity are provided across the phase diagram.

Abstract

A van Hove singularity (VHS) often significantly amplifies the electronic instability of a crystalline solid, including correlation-induced phenomena such as Hund's metallicity. We perform a systematic study on the interplay between Hund's coupling and electronic structures with a VHS focusing on Hund's metallicity. We construct a simplified tight-binding model targeting cubic perovskite materials and test the effects of the VHS utilizing dynamical mean-field theory with an exact diagonalization solver. The quasiparticle weight and the low-frequency power exponent of the self-energy provide a quantitative estimation of metallicity over the phase diagram. We find the VHS to substantially enhance Hund's metallicity. The results here suggest a range of parameters through which a VHS can bring great synergy with Hund's coupling.