Strongly correlated crystal-field approach to Mott insulator LaCoO3

TL;DR

This paper presents a strongly correlated crystal-field approach within the Quantum Atomistic Solid State Theory to accurately describe the electronic states and magnetic properties of the Mott insulator LaCoO3, emphasizing the importance of electron correlations and spin-orbit coupling.

Contribution

It introduces a novel strongly correlated crystal-field model that accounts for electron correlations and spin-orbit coupling, challenging previous band-structure results on LaCoO3.

Findings

No intermediate spin state in LaCoO3, contrary to band-structure predictions.

Excited states originate from high-spin 5T2g term, 12 meV above ground state.

Atomic-scale orbital magnetism is crucial for understanding 3d oxides.

Abstract

Our success in description of recent electron-spin-resonance results on Mott insulator LaCoO3, Phys. Rev. B 67 (2003) 172401, lies in taking into account strong electron correlations among d electrons and the relativistic spin-orbit coupling. In the developed by us Quantum Atomistic Solid State Theory (QUASST) we assume that the atomic-like integrity of the 3d^6 system is preserved in the Co^3+ ion in LaCoO3 and that intra-atomic correlations are much stronger than crystal field interactions. We conclude that in LaCoO3 there is no intermediate spin state as came out from band-structure calculations. The excited states originate from the high-spin 5T2g term, being 12 meV above the ground 1A1 state. We are convinced that many-electron CEF approach with strong correlations and the atomic-scale orbital magnetism is physically adequate approach to 3d oxides. Keywords: Mott insulator, crystal field, spin-orbit coupling, LaCoO3