{\it Ab initio} Studies on the Interplay between Spin-Orbit Interaction and Coulomb Correlation in Sr${}_2$IrO${}_4$ and Ba${}_2$IrO${}_4$

Abstract

{\it Ab initio} analyses of A${}_2$IrO${}_4$ (A=Sr, Ba) are presented. Effective Hubbard-type models for Ir 5$d$ $t_{2g}$ 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 Néel 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.

5 pages, 3 figures