Strong spin-orbital-coupling magnetic systems with the honeycomb structure can provide bond-directional interactions which may result in Kitaev quantum spin liquids and exotic anyonic excitations. However, one of the key ingredients in real materials−disorders−has been much less studied in Kitaev systems. Here we synthesized a trigonal SrIr2O6−δ with δ≈0.25, which consists of two-dimensional honeycomb Ir planes with edge-sharing IrO6 octahedra. First-principles computation and experimental measurements suggest that the electronic system is gapped, and there should be no magnetic moment as the Ir5+ ion has no unpaired electrons. However, significant magnetism has been observed in the material, and it can be attributed to disorders that are most likely from oxygen vacancies. No magnetic order is found down to 0.05 K, and the low-temperature magnetic properties exhibit power-law behaviors in magnetic susceptibility and zero-field specific heat, and a single-parameter scaling of the specific heat under magnetic fields. These results provide strong evidence for the existence of the random singlet phase in SrIr2O6−δ, which offers a different member to the family of spin-orbital entangled iridates and Kitaev materials.
@article{arxiv.2103.05820,
title = {Evidences for the random singlet phase in a new honeycomb iridate SrIr$_2$O$_{6-\delta}$},
author = {Pengbo Song and Kejia Zhu and Fan Yang and Yuan Wei and Lu Zhang and Huaixin Yang and Xian-Lei Sheng and Yang Qi and Jiamin Ni and Shiyan Li and Yanchun Li and Guanghan Cao and Zi Yang Meng and Wei Li and Youguo Shi and Shiliang Li},
journal= {arXiv preprint arXiv:2103.05820},
year = {2021}
}