Theoretical analysis of single-ion anisotropy in d cubed Mott insulators
The study derives analytical expressions for single-ion anisotropy (SIA) in d³ Mott insulators using strong-coupling perturbation theory, incorporating crystal field splitting, Hund's coupling, and spin-orbit coupling. It shows that the contribution from $e_g$ orbitals is crucial for SIA strength and determines whether the anisotropy favors an easy-plane or easy-axis configuration.