Orbital order in ZnV$_2$O$_4$

TL;DR

This study uses ab initio calculations to clarify the orbital order in ZnV2O4, showing that spin-orbit coupling and electronic correlations are key to understanding its magnetic and orbital ground state.

Contribution

It demonstrates that combining relativistic spin-orbit effects with electronic correlations in ab initio methods resolves previous controversies about orbital order in ZnV2O4.

Findings

LDA+U stabilizes staggered orbital order without spin-orbit effects.

Including spin-orbit coupling unquenches the orbital moment.

Results align with experimental magnetic moments.

Abstract

In view of recent controversy regarding the orbital order in the frustrated spinel ZnV2O4, we analyze the orbital and magnetic groundstate of this system within an ab initio density functional theory approach. While LDA+U calculations in the presence of a cooperative Jahn-Teller distortion stabilize an A-type staggered orbital order, the consideration of relativistic spin-orbit effects unquenches the orbital moment and leads to a uniform orbital order with a net magnetic moment close to the experimental one. Our results show that ab initio calculations are able to resolve the existing discrepancies in previous theories and that it is the spin-orbit coupling alongwith electronic correlations which play a significant role in determining the orbital structure in these materials.