Ab initio Studies on the Interplay between Spin-Orbit Interaction and Coulomb Correlation in Sr2IrO4 and Ba2IrO4

Ab initio analyses of A(2)IrO(4) (A = Sr; Ba) are presented. Effective Hubbard-type models for Ir 5d t(2g) manifolds downfolded from the global band structure are solved based on the dynamical mean-field theory. The results for A Sr and Ba correctly reproduce paramagnetic metals undergoing continuous transitions to insulators below the Neel temperature T-N. These compounds are classified not into Mott insulators but into Slater insulators. However, the insulating gap opens by a synergy of the Neel order and significant band renormalization, which is also manifested by a 2D bad metallic behavior in the paramagnetic phase near the quantum criticality.