Inelastic Neutron Scattering of the Spin-liquid Candidate Ba₃ZnRu₂O₉ and diluted Ba₃Zn(Ru_0.1Sb_0.9)₂O₉

Ba₃ZnRu₂O₉ (BZRO) is a 6-H perovskite compound that contains triangular lattice layers of S=3/2 Ru⁵⁺ dimers, and was reported to have no signatures of long-range-magnetic-order down to 37 mK and therefore put forward as a spin-liquid candidate.[1] We present inelastic neutron scattering measurments on BZRO powder, an array of BZRO crystals, and a diluted powder of Ba₃Zn(Ru_0.1Sb_0.9)₂O₉. The method of studying dilute and non-dilute materials in concert, along with support of density functional theory calculations, helps ameliorate the problem of many parameters in the magnetic Hamiltonian. So, while historical considerations of an analogous compound Ba₃CaRu₂O₉ have suggested these materials to be magnetic dimers with perturbative inter-dimer interactions,[2] our findings show BZRO to be away from the dimer regime with a strikingly small (vanishing?) gap in the magnetic correlations and a bandwidth of the similar magnitude as the intra-dimer interaction.

[1] I. Terasaki, and co-authors, J. Phys. Soc. Jpn. 86, 033702 (2017) [4 Pages]

[2] J. Darriet, and co-authors, J. Phys. Chem. Solids 44 (1983) pp. 269-212.