Enhanced Crystal Field Splitting and Orbital Selective Coherence by Strong Correlations in V_2O_3

TL;DR

This paper investigates how strong electronic correlations in V2O3 enhance crystal field splitting and lead to orbital-selective coherence, explaining the metal-insulator transition with detailed theoretical and spectral analysis.

Contribution

It combines advanced density functional theory and dynamical mean-field theory to reveal correlation-driven effects on crystal field splitting and orbital coherence in V2O3.

Findings

Correlation enhances crystal field splitting within t2g orbitals.

a1g orbitals show coherent quasiparticle behavior at 400 K.

Spectral functions agree with recent photoemission experiments.

Abstract

We present a study of the paramagnetic metallic and insulating phases of vanadium sesquioxide by means of the $N$th order muffin-tin orbital implementation of density functional theory combined with dynamical mean-field theory. The transition is shown to be driven by a correlation-induced enhancement of the crystal field splitting within the $t_{2g}$ manifold, which results in a suppression of the hybridization between the $a_{1g}$ and $e_g^{\pi}$ bands. We discuss the changes in the effective quasi-particle band structure caused by the correlations and the corresponding self-energies. At temperatures of about 400 K we find the $a_{1g}$ orbitals to display coherent quasi-particle behavior, while a large imaginary part of the self-energy and broad features in the spectral function indicate that the $e_g^{\pi}$ orbitals are still far above their coherence temperature. The local spectral functions are in excellent agreement with recent bulk sensitive photoemission data. Finally, we also make a prediction for angle-resolved photoemission experiments by calculating momentum-resolved spectral functions.