Resonant inelastic x-ray scattering in Ca3LiOsO6 from first-principles

We have investigated the electronic and magnetic properties of the transition metal oxide (TMO) Ca ₃LiOsO ₆ within the density functional theory (DFT) using the generalized gradient approximation while taking into account strong Coulomb correlations (GGA+ U ) in the framework of the fully relativistic spin-polarized Dirac linear muffin-tin orbital band-structure method. Ca ₃LiOsO ₆ is an insulator and forms the K 4 CdCl 6 -type crystal structure with relatively high Néel temperature T N = 117 K. Despite of the large strength of spin–orbit coupling, it has only a small effect on the electronic and magnetic properties of Ca ₃LiOsO ₆ . We have also investigated theoretically the x-ray absorption spectra (XAS), x-ray magnetic circular dichroism (XMCD) and resonant inelastic x-ray scattering (RIXS) spectra at the Os L 3 edge. The experimentally measured RIXS spectrum of Ca ₃LiOsO ₆ in addition to the elastic scattering peak at 0 eV possesses a sharp feature below 2 eV corresponding to transitions within the Os t 2 g levels. The excitation located at 4.5 eV is due to t 2 g → e g transitions. The third wide structure situated at 6–8 eV appears due to ligand-to-metal charge transfer excitations: d − d transitions to the Os t 2 g manifold from the Os 5 d O states derived from the ”tails” of oxygen 2 p states. The high energy structure at 10–11.5 eV is due to Os 5 d O → e g interband transitions. At higher energy above 11 eV transitions from the Os 5 d O states to the empty Ca 5 d states are located. We have investigated the effect of SO coupling, Coulomb correlations and core-hole effect on the energy band structure, XAS, XMCD, and RIXS spectra in Ca ₃LiOsO ₆.