Crystal-field effects competing with spin-orbit interactions in NaCeO$_2$

TL;DR

This study uses computational methods to analyze the electronic structure of NaCeO$_2$, confirming it as a 4f magnet with significant crystal-field and spin-orbit interactions, validated by neutron scattering data.

Contribution

The paper benchmarks embedded-cluster quantum chemical calculations for 4f systems, demonstrating their accuracy in reproducing experimental spectra of NaCeO$_2$.

Findings

Good agreement between computations and neutron scattering data.

NaCeO$_2$ exhibits intermediate coupling with strong crystal-field and spin-orbit effects.

Weak vibronic effects simplify spectral interpretation.

Abstract

Ce compounds feature a remarkable diversity of electronic properties, which motivated extensive investigations over the last decades. Inelastic neutron scattering represents an important tool for understanding their underlying electronic structures but in certain cases a straightforward interpretation of the measured spectra is hampered by the presence of strong vibronic couplings. The latter may give rise to extra spectral features, which complicates the mapping of experimental data onto standard multiplet diagrams. To benchmark the performance of embedded-cluster quantum chemical computational schemes for the case of $4f$ systems, we here address the Ce 4$f^1$ multiplet structure of NaCeO$_2$, an antiferromagnet with $D_{2d}$ magnetic-site symmetry for which neutron scattering measurements indicate only weak vibronic effects. Very good agreement with the experimental results is found in the computations, which validates our computational approach and confirms NaCeO$_2$ as a 4$f$ magnet in the intermediate coupling regime with equally strong 4$f$-shell spin-orbit and crystal-field interactions.