Ruthenium trihalides RuX3 (X = Cl, Br, I) provide a tunable platform for Kitaev magnetism in two-dimensional van der Waals materials. Despite their similar crystal structures and zigzag antiferromagnetic order, RuBr3 exhibits a higher N\'eel temperature (TN) than RuCl3, suggesting their distinct proximity to the Kitaev quantum spin liquid phase. Using Ru L3-edge resonant x-ray scattering, we show that, while the long-range zigzag order in RuBr3 disappears at TN, the zigzag correlations that persist well above TN show a pronounced spectral weight redistribution along the interlayer direction. These results suggest that the enhanced interlayer magnetic interactions driven by the extended Br 4p orbitals stabilize three-dimensional zigzag correlations in RuBr3.
@article{arxiv.2604.05346,
title = {Three-dimensional zigzag correlations in the van der Waals Kitaev magnet RuBr$_3$},
author = {H. Gretarsson and R. Iwazaki and F. Sato and H. Gotou and S. Francoual and J. Nasu and Y. Imai and K. Ohgushi and J. Chaloupka and B. Keimer and H. Suzuki},
journal= {arXiv preprint arXiv:2604.05346},
year = {2026}
}