Spin-orbit-entangled state of BaCaOsO studied by O -edge resonant inelastic X-ray scattering and Raman spectroscopy

Okamoto, Jun*; Shibata, Goro ; Fujimori, Atsushi; 9 of others*

Transition-metal ions with 5 electronic configuration in a cubic crystal field are prone to have a vanishing dipolar magnetic moment but finite higher-order multipolar moments, and they are expected to exhibit exotic physical properties. Through an investigation using resonant inelastic X-ray spectroscopy (RIXS), Raman spectroscopy, and theoretical ligand-field multiplet and ab initio calculations, we fully characterized the electronic structure of BaCaOsO, particularly, the crystal field symmetry of the 5 electrons in this anomalous material. The low-energy multiplet excitations from RIXS at the oxygen edge and Raman-active phonons both show no splitting, confirming the absence of Jahn-Teller distortion. These findings are consistent with the ground state with the "hidden order" of magnetic octupoles.