Fig. 1: Energy diagrams of the Os6+ (5d2) ion in the cubic (Oh) crystal field.
a One-electron energy diagram. ΔLF is the t2g-eg splitting. Spin-orbit coupling (SOC) further splits the t2g level into \({j}_{{\rm{eff}}}=\frac{1}{2}\) and \({j}_{{\rm{eff}}}=\frac{3}{2}\) levels separated by \(\frac{3}{2}\zeta\), and the \({j}_{{\rm{eff}}}=\frac{3}{2}\) level is occupied by two electrons. b Two-electron energy diagram. The \({t}_{2g}^{2}\) part of the d2 multiplet is shown whereas the t2geg part is located at higher energies separated by ~ ΔLF. Due to the ligand field (LF) of cubic symmetry, the Jeff = 2 ground state is split by a ‘residual’ cubic splitting Δc into the non-Kramers Eg doublet and the T2g triplet. The first Jeff = 0 excited state appears ΔE ~ 0.4 eV above the ground state, and the first Jeff = 1 excited state ~ 0.065 eV above it.
