Correlated Ligand Electrons in the Transition-Metal Oxide SrRuO$_3$

TL;DR

This study investigates the role of ligand p electron correlations in the electronic structure of SrRuO3, revealing distortions in oxygen 2p states that highlight the importance of ligand electron interactions in correlated and topological materials.

Contribution

It provides experimental evidence of ligand p electron correlations affecting the electronic structure in a transition-metal oxide with topological states.

Findings

O 2p PDOS is distorted from first-principles predictions

Ligand electron correlation is crucial for understanding p-d hybridized states

Ligand correlations influence the electronic properties of topological materials

Abstract

In transition-metal compounds, the transition-metal d electrons play an important role in their physical properties; however, the effects of the electron correlation between the ligand p electrons have not been clear yet. In this Letter, the Ru 4d and O 2p partial density of states (PDOS) in transition-metal oxide SrRuO$_3$ involving Weyl fermions are investigated by resonant photoemission spectroscopy. The observations demonstrate that the O 2p PDOS is distorted from that predicted by first-principles calculations than the Ru 4d PDOS. The results indicate that the electron correlation in the ligand orbitals will be important to understand the electronic structure of the p-d hybridized state in strongly correlated electron systems, even with topological states.