Orbital state and magnetic properties of LiV_2 O_4

TL;DR

This study combines density functional theory and dynamical mean-field theory to analyze the orbital and magnetic properties of LiV_2 O_4, revealing orbital splitting, electron localization, and magnetic susceptibility consistent with experiments.

Contribution

It provides a detailed theoretical analysis of LiV_2 O_4's orbital state and magnetic behavior using advanced computational methods, offering insights into its heavy fermion-like properties.

Findings

Orbital splitting with a_{1g} and e_{g}^{pi} orbitals crossing the Fermi level.

Electron localization in the a_{1g} orbital due to Coulomb interactions.

Theoretical susceptibility matches experimental Curie-Weiss behavior.

Abstract

LiV_2 O_4 is one of the most puzzling compounds among transition metal oxides because of its heavy fermion like behavior at low temperatures. In this paper we present results for the orbital state and magnetic properties of LiV_2 O_4 obtained from a combination of density functional theory within the local density approximation and dynamical mean-field theory (DMFT). The DMFT equations are solved by quantum Monte Carlo simulations. The trigonal crystal field splits the V 3d orbitals such that the a_{1g} and e_{g}^{pi} orbitals cross the Fermi level, with the former being slightly lower in energy and narrower in bandwidth. In this situation, the d-d Coulomb interaction leads to an almost localization of one electron per V ion in the a_{1g} orbital, while the e_{g}^{pi} orbitals form relatively broad bands with 1/8 filling. 2The theoretical high-temperature paramagnetic susceptibility chi(T) follows a Curie-Weiss law with an effective paramagnetic moment p_{eff}=1.65 in agreement with the experimental results.