The electronic structure of Sr3CuIrO6, a model system for the 5d Ir ion in an octahedral environment, is studied through a combination of resonant inelastic x-ray scattering (RIXS) and theoretical calculations. RIXS spectra at the Ir L3-edge reveal an Ir t2g manifold that is split into three levels, in contrast to the expectations of the strong spin-orbit-coupling limit. Effective Hamiltonian and abinito quantum chemistry calculations find a strikingly large non-cubic crystal field splitting comparable to the spin-orbit coupling, which results in a strong mixing of the jeff=1/2 and jeff=3/2 states and modifies the isotropic wavefunctions on which many theoretical models are based.
@article{arxiv.1209.5294,
title = {Testing the validity of the strong spin-orbit-coupling limit for octahedrally coordinated iridates in a model system Sr$_3$CuIrO$_6$},
author = {X. Liu and Vamshi M. Katukuri and L. Hozoi and Wei-Guo Yin and M. P. M. Dean and M. H. Upton and Jungho Kim and D. Casa and A. Said and T. Gog and T. F. Qi and G. Cao and A. M. Tsvelik and Jeroen van den Brink and J. P. Hill},
journal= {arXiv preprint arXiv:1209.5294},
year = {2012}
}