A-site hybridization wave induced Mott transition in ABO$_3$ perovskites

Correlated insulators in quantum materials including ABO$_3$ perovskites are traditionally classified as Mott-Hubbard or charge-transfer insulators, focussing exclusively on the B-site cation and the ligand (oxygen). In this work, we propose a unique kind of {\it hybridization wave} induced Mott insulator, where a spatial modulation in the hybridization between the ligand and the A-site cation triggers a Mott transition on the correlated B-site transition metal cation. Our work is relevant to a variety of ABO$_3$ perovskites such as BiNiO$_3$ and PbCrO$_3$ with A-site cations having extended $6s$ orbitals. Using {\it ab initio} electronic structure and slave rotor theory, we show that pressure tunes the ligand energy, driving a colossal volume-changing Mott transition, as observed in these compounds, from a Mott insulator induced by an A-O hybridization wave into a uniform metal at high pressure.