New Paradigms arising from Spin- Orbit Coupling and Correlations in Iridates
The energy scales associated with various solid interactions such as crystal field splitting, Coulomb correlations and spin orbit coupling vary across the chemical periodic table. However, for iridium oxides a reasonable balance is established among these interactions, giving rise to a plethora of exotic ground states. However, the origin of these states are much debated. The present discussion is about to the study of few iridium oxides that have been widely debated in literature.
We adopt the density functional theory (DFT) formalism considering Hamiltonians employing conventional homogeneous electron gas approximation and also semi-local approximations. By large the work intends to discuss the nature and origin of the insulating gap and magnetic properties in iridium oxides with a critique to the its e_ects of the underlying lattice, Coulomb correlations and spin-orbit coupling (SOC). The failure of DFT in predicting the physical properties of iridium oxides is not surprising as approximations to the exchange-correlation term of the crystal Hamiltonian does not properly account the extent of hybridization between the atomic orbitals. However, we find that Hamiltonians that improve these limitations with semi-local and / or non-local corrections reproduce the experimental observations with much more consistency, with no parametric
approximations and assumptions at the outset. In general, our calculations shows that the effects of SOC in iridium oxides are nominal with little or no effect on its role in rendering an insulating gap, although it imparts a large magneto-crystalline anisotropy.
Host: Dr. Se Young Park