Magnetic moment suppression in Ba3CoRu2O9: hybridization effect

TL;DR

This paper investigates the magnetic properties of Ba3CoRu2O9, demonstrating that the observed magnetic moment suppression results from Ru 4d and O 2p hybridization rather than an unusual orbital state.

Contribution

It clarifies the origin of magnetic moment suppression in Ba3CoRu2O9 by ruling out the proposed orbital state and highlighting hybridization effects.

Findings

The proposed orbital state contradicts Hund's rule.

Small crystal-field splitting prevents the orbital state.

Magnetic suppression is due to Ru 4d and O 2p hybridization.

Abstract

An unusual orbital state was recently proposed to explain the magnetic and transport properties of Ba$_3$CoRu$_2$O$_9$ [Phys. Rev. B. {\bf 85}, 041201 (2012)]. We show that this state contradicts to the first Hund's rule and does not realize in the system under consideration because of a too small crystal-field splitting in the $t_{2g}$ shell. A strong suppression of the local magnetic moment in Ba$_3$CoRu$_2$O$_9$ is attributed to a strong hybridization between the Ru 4$d$ and O 2$p$ states.