Understanding the Electronic Structure of IrO2 Using Hard-X-ray Photoelectron Spectroscopy and Density-Functional Theory

The electronic structure of ${\mathrm{IrO}}_{2}$ has been investigated using hard x-ray photoelectron spectroscopy and density-functional theory. Excellent agreement is observed between theory and experiment. We show that the electronic structure of ${\mathrm{IrO}}_{2}$ involves crystal field splitting of the iridium $5d$ orbitals in a distorted octahedral field. The behavior of ${\mathrm{IrO}}_{2}$ closely follows the theoretical predictions of Goodenough for conductive rutile-structured oxides [J. B. Goodenough, J. Solid State Chem. 3, 490 (1971)]. Strong satellites associated with the core lines are ascribed to final state screening effects. A simple plasmon model for the satellites applicable to many other metallic oxides appears to be not valid for ${\mathrm{IrO}}_{2}$.