Hybridization-switching induced Mott transition in ABO$_3$ perovskites

TL;DR

This paper introduces a new type of Mott transition in ABO$_3$ perovskites driven by hybridization switching involving A-site orbitals and ligand holes, leading to pressure-induced insulator-metal transitions with volume collapse.

Contribution

It proposes the concept of hybridization-switching induced Mott transition and demonstrates its occurrence in ABO$_3$ perovskites through ab initio and slave rotor calculations.

Findings

Hybridization switching triggers Mott insulating state in ABO$_3$ perovskites.

Pressure induces insulator-metal transition with volume collapse.

A-site orbitals and ligand hybridization are crucial for the transition.

Abstract

We propose the concept of "hybridization-switching induced Mott transition" which is relevant to a broad class of ABO$_3$ perovskite materials including BiNiO$_3$ and PbCrO$_3$ which feature extended $6s$ orbitals on the A-site cation (Bi or Pb), and A-O covalency induced ligand holes. Using {\it ab initio} electronic structure and slave rotor theory calculations, we show that such systems exhibit a breathing phonon driven A-site to oxygen hybridization-wave instability which conspires with strong correlations on the B-site transition metal ion (Ni or Cr) to induce a Mott insulator. These Mott insulators with active A-site orbitals are shown to undergo a pressure induced insulator to metal transition accompanied by a colossal volume collapse due to ligand hybridization switching.