Proposed Orbital Ordering in MnV2O4 from First-principles Calculations

TL;DR

This study uses first-principles density functional calculations to propose an orbital ordering pattern in MnV2O4, highlighting the importance of correlation effects and their influence on structural and magnetic properties.

Contribution

It introduces a novel orbital ordering pattern in MnV2O4 derived from first-principles calculations, emphasizing the role of correlation effects in structural transitions.

Findings

Orbital chains run along a and b directions with alternating 45-degree rotations.

Correlation effects are crucial for correct symmetry description.

The proposed orbital order favors noncollinear magnetic ordering.

Abstract

Based on density functional calculations, we propose a possible orbital ordering in MnV2O4 which consists of orbital chains running along crystallographic a and b directions with orbitals rotated alternatively by about 45 degrees within each chain. We show that the consideration of correlation effects as implemented in the local spin density approximation (LSDA)+U approach is crucial for a correct description of the space group symmetry. This implies that the correlation-driven orbital ordering has a strong influence on the structural transitions in this system. Inclusion of spin-orbit effects does not seem to influence the orbital ordering pattern. We further find that the proposed orbital arrangement favours a noncollinear magnetic ordering of V spins, as observed experimentally. Exchange couplings among V spins are also calculated and discussed.