Electronic excitations in 5d4J=0Os4+ halides studied by resonant inelastic x-ray scattering and optical spectroscopy

The cubic halides K${}₂$OsCl${}₆$, K${}₂$OsBr${}₆$, and Rb${}₂$OsBr${}₆$ are found to be excellent realizations of spin-orbit-entangled nonmagnetic $J$=0 compounds in the intermediate coupling regime. The two complementary techniques of resonant inelastic x-ray scattering and optical spectroscopy allow the authors to draw a comprehensive picture of the electronic excitations and to assess the electronic structure. The accurate set of electronic parameters such as spin-orbit coupling, Hund's coupling, crystal-field splitting, Mott gap, and charge-transfer energy will serve as a solid reference for future studies on Os compounds.