# Interplay of strong correlations and covalency in ionic band insulators

## TL;DR

This paper investigates how electronic correlations influence the insulating behavior of ionic band insulators, revealing that correlations can either promote metallicity or insulating states depending on the balance of ionicity and covalency.

## Contribution

It demonstrates how electronic correlations affect the metal-insulator transition in ionic band insulators using a two-orbital Hubbard model within DMFT.

## Key findings

- Correlations turn a metal into a band insulator when ionicity equals covalency.
- Correlations favor metallicity when covalency is less than ionicity.
- Correlations favor insulating behavior when covalency exceeds ionicity.

## Abstract

We address the role of electronic correlations in different kinds of band insulators by using the two-orbital Hubbard model within the dynamical mean-field theory (DMFT). An intriguing finding is that electronic correlations turn a metal into a band insulator when ionicity and covalency are equal in ratio.We conclude that the electronic correlations favour metallicity when the covalency is smaller than the ionicity, while they favour insulating behaviour when the covalency is greater than ionicity.