Dependence of band gaps in d-electron perovskite oxides on magnetism

TL;DR

This study reveals how magnetic configurations influence band gaps in d-electron perovskite oxides, showing that the effect depends on orbital character and antiferromagnetic contacts, which has implications for electronic properties and applications.

Contribution

The paper uncovers the dependence of band gap magnitudes on magnetic order and orbital character, introducing new rules linking antiferromagnetic contacts to electronic structure in perovskite oxides.

Findings

Band gap dependence varies with orbital character and magnetic contacts.

Weak dependence in Mott insulators, strong in charge transfer insulators.

Magnetic order affects both band gaps and lattice distortions.

Abstract

Understanding the controlling principles of band gaps trends in d electron perovskites is needed both for gauging metal-insulator transitions, as well as their application in catalysis and doping. The magnitude of this band gap is rather different for different magnetic spin configurations. We find via electronic structure theory that the factors that connect gapping magnitudes to magnetism depend on the nature of the band edge orbital character (BEOC) and surprisingly scale with the number of antiferromagnetic contacts z$_i$ between neighboring transition metal ions. The dependence is weak when the BEOC are (d,d)-like ("Mott insulators"), whereas this dependence is rather strong in (p,d)-like ("charge transfer" insulators). These unexpected rules are traced to the reduced orbital interactions through the increase in the number of antiferromagnetic contacts between transition metal ions. The impact of magnetic order is not limited to the band gap magnitude and includes also the magnitude of lattice distortions connected to the electronic structure. These results highlight the importance of establishing in electronic structure theory of gap-related phenomena (doping, transport, metal-insulator transitions, conductive interfaces) the appropriate magnetic order.