The complex iridium oxide Na3Ir3O8 with a B-site ordered spinel structure was synthesized in single crystalline form, where the chiral hyper-kagome lattice of Ir atoms, as observed in the spin-liquid candidate Na4Ir3O8, was identified. The average valence of Ir is 4.33+ and, therefore, Na3Ir3O8 can be viewed as a doped analogue of the hyper-kagome spin liquid with Ir4+. The transport measurements showed that Na3Ir3O8 is in fact a semi-metal. The electronic structure calculation demonstrated that the strong spin-orbit coupling of Ir yields the semi-metallic state out of an otherwise band insulating state, which may harbor exotic topological effects embedded in the hyper-kagome lattice.
@article{arxiv.1311.2885,
title = {Spin-orbit coupling induced semi-metallic state in the 1/3 hole doped hyper-kagome Na3Ir3O8},
author = {T. Takayama and A. Matsumoto and J. Nuss and A. Yaresko and K. Ishii and M. Yoshida and J. Mizuki and H. Takagi},
journal= {arXiv preprint arXiv:1311.2885},
year = {2013}
}