We investigate the magnetic ground state of single crystals of the ruthenium-dimer-based hexagonal perovskite Ba3ZnRu2O9 using magnetic susceptibility and resonant inelastic x-ray scattering (RIXS) measurements. While a previous study on powder samples exhibited intriguing magnetic behavior, questions about whether the spin state within a Ru2O9 dimer is a conventional S=3/2 dimer or an orbital-selective S=1 dimer were raised. The RIXS spectra reveal magnetic excitations from Hund's intraionic multiplet and intradimer spin-triplet transitions. The observed transition energies of the Hund's intraionic multiplets align with the S=3/2 ground state, contrasting with the theoretically proposed orbital-selective S=1 dimer state. High-temperature magnetic susceptibility analysis confirms the realization of the spin S=3/2 dimer state, and the extracted intradimer coupling is consistent with the spin-triplet transition energy observed in the RIXS spectra. These results highlights the ability of "spectroscopic fingerprinting" by RIXS to determine the magnetic ground states of complex materials.
@article{arxiv.2411.15383,
title = {Magnetic ground state of the dimer-based hexagonal perovskite Ba$_{3}$ZnRu$_{2}$O$_{9}$},
author = {S. Hayashida and H. Gretarsson and P. Puphal and M. Isobe and E. Goering and Y. Matsumoto and J. Nuss and H. Takagi and M. Hepting and B. Keimer},
journal= {arXiv preprint arXiv:2411.15383},
year = {2025}
}