Effect of spin orbit coupling and HubbardUon the electronic structure of IrO2

Abstract

We have studied in detail the electronic structure of IrO${}_{2}$ including spin orbit coupling (SOC) and electron-electron interaction, both within the generalized gradient approximation plus Hubbard $U$ (GGA+U) and GGA plus dynamical mean field theory (GGA+DMFT) approximations. Our calculations reveal that the Ir ${t}_{2g}$ states at the Fermi level largely retain the ${J}_{\mathrm{eff}}=\frac{1}{2}$ character, suggesting that this complex spin orbit entangled state may be robust even in metallic IrO${}_{2}$. We have calculated the phase diagram for the ground state of IrO${}_{2}$ as a function of $U$ and find a metal insulator transition that coincides with a magnetic phase change, where the effect of SOC is only to reduce the critical values of $U$ necessary for the transition. We also find that dynamic correlations, as given by the GGA+DMFT calculations, tend to suppress the spin-splitting, yielding a Pauli paramagnetic metal for moderate values of the Hubbard $U$. Our calculated optical spectra and photoemission spectra including SOC are in good agreement with experiment, demonstrating the importance of SOC in IrO${}_{2}$.