Variational study of the antiferromagnetic insulating phase of V2O3 based on Nth order Muffin-Tin-Orbitals

TL;DR

This study re-examines the low-temperature antiferromagnetic insulating phase of V2O3 using Nth order muffin-tin orbitals, revealing new insights into hopping integrals and magnetic structure, but also highlighting discrepancies with experimental data.

Contribution

It introduces a variational approach based on NMTO-derived hopping parameters to analyze V2O3's ground state, emphasizing the importance of in-plane hopping and non-local correlations.

Findings

In-plane hopping integrals are as significant as out-of-plane ones.

Stable molecular formations are not energetically favorable in this phase.

The ground state predicted differs from experimental observations, indicating complex electronic correlations.

Abstract

Motivated by recent results of $N$th order muffin-tin orbital (NMTO) implementation of the density functional theory (DFT), we re-examine low-temperature ground-state properties of the anti-ferromagnetic insulating phase of vanadium sesquioxide V$_2$O$_3$. The hopping matrix elements obtained by the NMTO-downfolding procedure differ significantly from those previously obtained in electronic structure calculations and imply that the in-plane hopping integrals are as important as the out-of-plane ones. We use the NMTO hopping matrix elements as input and perform a variational study of the ground state. We show that the formation of stable molecules throughout the crystal is not favorable in this case and that the experimentally observed magnetic structure can still be obtained in the atomic variational regime. However the resulting ground state (two $t_{2g}$ electrons occupying the degenerate $e_g$ doublet) is in contrast with many well established experimental observations. We discuss the implications of this finding in the light of the non-local electronic correlations certainly present in this compound.