Evidence of Slater-type mechanism as origin of insulating state in Sr 2 IrO 4

Abstract For iridates with large spatially extended 5 d orbitals, it may be anticipated that distant neighbor interactions would play a crucial role in their ground state properties. From this perspective, we investigate the magnetic structure of Sr 2 IrO 4 by including interactions beyond first and second neighbors, via supercell modeling. Adopting to first-principles scalar relativistic methods, it is found that the minimum in total energy among various magnetic structures correspond to a type antiferromagnetic ordering of the Ir ions for which the magnitude of the electronic gap, that of the Ir local moments and, the facsimile of the two-peaked structure in the optical conductivity spectra of Sr 2 IrO 4 were found to be in good agreement with the experiments. The results unequivocally show that the origin of the electronic gap in Sr 2 IrO 4 is due to an unconventional antiferromagnetic ordering of Ir ions, thereby classifying the system as a Slater magnet, rather than the spin–orbit coupling driven Mott insulator.