Post-perovskite CaIrO3: a conventional Slater type antiferromagnetic insulator

Abstract

To resolve the controversy of whether or not the origin of an electronic gap in antiferromagnetic post-perovskite (pPv) CaIrO₃ is due to Coulomb repulsion or spin–orbit coupling, and/or both, we have performed comprehensive full potential density functional theory based calculations. A rather consistent electronic structure, which explains the origin and magnitude of the electronic gap, inter-band d–d transition energies, high thermopower and large magneto-crystalline anisotropy, is obtained with the use of a modified Becke–Johnson (mBJ) exchange potential. Fundamentally, mBJ calculations correctly capture the strong interplay of the crystal field and long range antiferromagnetic ordering of Ir spins as the mechanism that drives pPv-CaIrO₃ to an insulating state. Based on our findings, we propose that pPv-CaIrO₃ is a conventional Slater type antiferromagnetic insulator.