Crystal field and magnetic structure of UO$_{2}$

TL;DR

This paper provides a detailed theoretical analysis of UO$_{2}$'s electronic and magnetic properties, accurately reproducing experimental crystal field excitations and confirming the 3-k magnetic structure as the ground state.

Contribution

It combines DFT+$U$ calculations with a model Hamiltonian to accurately describe UO$_{2}$'s electronic structure and magnetic ground state, advancing understanding of actinide materials.

Findings

Reproduces crystal field excitation energies in good agreement with experiments.

Confirms the 3-k magnetic structure as the T=0 K ground state.

Provides insights into the interplay of Coulomb, spin-orbit, and crystal field effects.

Abstract

The properties of UO$_{2}$ result from rich $f$-electron physics, including electronic Coulomb interactions, spin-orbit and crystal field effects, as well as inter-ionic multipolar coupling. We present a comprehensive theoretical study of the electronic structure of UO$_{2}$ using a combined application of self-consistent DFT+$U$ calculations and a model Hamiltonian. The $\Gamma_{5}$ ground state of U$^{4+}$ and the energies of crystal field excitations $\Gamma_{5} \rightarrow \Gamma_{3,4,1}$ are reproduced in very good agreement with experiment. We also investigate competing non-collinear magnetic structures and confirm 3-k as the T=0 K ground state magnetic structure of UO$_2$.