Charge dynamics and metal-insulator transition in perovskite SrIr_1−xSn_xO₃

We investigate the variation of charge dynamics upon the metal-insulator transition for perovskite SrIr₁−_xSn_xO₃ by employing the optical spectroscopy. The Dirac semimetal of SrIrO₃ turns into the antiferromagnetic insulator with a gap of 0.1 eV by the Sn-substitution, accompanying the reconstruction of electronic structure on an energy scale of 1 eV. The spectral intensity of optical excitation between J_eff = 1=2-orbitals is significantly reduced with increasing x, while that between the J_eff = 3=2- and 1=2-orbital shows merely moderate x-dependence. We anticipate that the substituted Sn significantly renormalizes the effective bandwidth of J_eff = 1=2-orbital while modestly changing the J_eff = 3=2-orbital.