Se p 20 12 Magnetic couplings , optical spectra , and spin - orbit exciton in 5 d electron Mott insulator Sr 2 IrO 4 Beom

Based on the microscopic model including spin-orbit coupling, on-site Coulomb and Hund’s interactions, as well as crystal field effects, we have investigated magnetic and optical properties of Sr2IrO4. Taking into account all intermediate state multiplets generated by virtual hoppings of electrons, we calculated the isotropic, pseudodipolar, and Dzyaloshinsky-Moriya coupling constants, which describe the experiment quite well. The optical conductivity σ(ω) evaluated by the exact diagonalization method shows two peaks at ∼ 0.5 and ∼ 1.0 eV in agreement with experiment. The two peak structure of σ(ω) arises from the unusual Fano-type overlap between electron-hole continuum of the Jeff = 1/2 band and the intrasite spin-orbit exciton observed recently in Sr2IrO4.