Magnetic Order in Transition Metal Oxides with Orbital Degrees of Freedom

TL;DR

This paper explores how orbital degrees of freedom influence magnetic ordering in cubic transition metal oxides, revealing different magnetic phases driven by orbital interactions and fluctuations.

Contribution

It provides a theoretical analysis of magnetic phases in transition metal oxides considering orbital degeneracy and fluctuations, explaining experimental observations.

Findings

e_g orbital ordering explains A-type antiferromagnetism in KCuF3 and LaMnO3

t_{2g} orbital fluctuations induce transitions from orbital liquid to ordered states

Orbital fluctuations compete with Jahn-Teller effects, affecting magnetic order in LaVO3 and YVO3

Abstract

We investigate the frustrated magnetic interactions in cubic transition metal oxides with orbital degeneracy. The $e_g$ orbitals order easier and their ordering explains the $A$-type antiferromagnetic phase in KCuF$_3$ and LaMnO$_3$. In $t_{2g}$ systems the magnetic order changes at a transition from an orbital liquid to orbital ordered states. The fluctuations of $t_{2g}$ orbitals play a prominent role in LaVO$_3$ and YVO$_3$, where they compete with the Jahn-Teller effect and trigger the C-type antiferromagnetic order.