Multiband $d-p$ model and self-doping in the electronic structure of Ba${}_2$IrO${}_4$

Abstract

We introduce and investigate the multiband $d-p$ model describing a IrO${}_4$ layer (such as realized in Ba${}_2$IrO${}_4$) where all $34$ orbitals per unit cell are partly occupied, i.e., $t_{2g}$ and $e_g$ orbitals at iridium and $2p$ orbitals at oxygen ions. The model takes into account anisotropic iridium-oxygen $d-p$ and oxygen-oxygen $p-p$ hopping processes, crystal-field splittings, spin-orbit coupling, and the on-site Coulomb interactions, both at iridium and at oxygen ions. We show that the predictions based on assumed idealized ionic configuration (with $n_0=5+4\times 6=29$ electrons per IrO${}_4$ unit) do not explain well the independent \textit{ab initio} data and the experimental data for Ba${}_2$IrO${}_4$. Instead we find that the total electron density in the $d-p$ states is smaller, $n=29-x<n_0$ ($x>0$). When we fix $x=1$, the predictions for the $d-p$ model become more realistic and weakly insulating antiferromagnetic ground state with the moments lying within IrO${}_2$ planes along (110) direction is found, in agreement with experiment and \textit{ab initio} data. We also show that: (i) holes delocalize over the oxygen orbitals and the electron density at iridium ions is enhanced, hence (ii) their $e_g$ orbitals are occupied by more than one electron and have to be included in the multiband $d-p$ model describing iridates.

12 pages, 4 figures

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Cited by in corpus (4)

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• Possible superconductivity induced by a large spin-orbit coupling in carrier doped iridium oxide insulators: A weak coupling approach
• $d-p$ model and spin-orbital order in the vanadium perovskites
• On the Neglect of Local Coulomb Interaction on Oxygens in Perovskites Described by the Multi-band $d-p$ Model