Resonant inelastic x-ray scattering of the Jeff= 12 Mott insulator Sr2IrO4 from density functional theory

Abstract

We have investigated the electronic structure of Sr2IrO4 within density functional theory using the generalized gradient approximation while considering strong Coulomb correlations in the framework of the fully relativistic spin-polarized Dirac linear muffin-tin orbital band-structure method. We have investigated x-ray absorption spectra, x-ray magnetic circular dichroism, and resonant inelastic x-ray scattering (RIXS) spectra at the Ir K, L3, M3, M5, and O K edges. The calculated results are in good agreement with experimental data. The RIXS spectrum of Sr2IrO4 at the Ir L3 edge possesses a sharp feature <1.5 eV corresponding to transitions within the Ir t2g levels. The excitation located from 2 to 5 eV is due to t2g → eg transitions. The third wide structure situated at 5-12eV appears due to charge transfer transitions. We have found that the theory reproduces well the shape and energy position of the low-energy feature in the oxygen O K RIXS spectrum, but to obtain the correct positions of the second and third peaks, a self-interaction-correction-like orbital-dependent potential Vl must be included in the Hamiltonian to correct the position of the oxygen 2p band. We have found that the dependence of the RIXS spectrum at the oxygen K edge on the incident photon energy and the momentum transfer vector Q is much stronger than the correspondent dependence at the Ir L3 edge.