Entanglement of spin and orbital degrees of freedom drives the formation of novel quantum and topological physical states. Discovering new spin-orbit entangled ground states and emergent phases of matter requires both experimentally probing the relevant energy scales and applying suitable theoretical models. Here we report resonant inelastic x-ray scattering measurements of the transition metal oxides Ca3LiOsO6 and Ba2YOsO6. We invoke an intermediate coupling approach that incorporates both spin-orbit coupling and electron-electron interactions on an even footing and reveal the ground state of 5d3 based compounds, which has remained elusive in previously applied models, is a novel spin-orbit entangled J=3/2 electronic ground state. This work reveals the hidden diversity of spin-orbit controlled ground states in 5d systems and introduces a new arena in the search for spin-orbit controlled phases of matter.
@article{arxiv.1610.02375,
title = {Spin-orbit coupling controlled $J=3/2$ electronic ground state in 5$d^{3}$ oxides},
author = {A. E. Taylor and S. Calder and R. Morrow and H. L. Feng and M. H. Upton and M. D. Lumsden and K. Yamaura and P. M. Woodward and A. D. Christianson},
journal= {arXiv preprint arXiv:1610.02375},
year = {2017}
}