We provide experimental evidence for the absence of a magnetic moment in bulk RuO2, a candidate altermagnetic material, by using a combination of M\"ossbauer spectroscopy, nuclear forward scattering, inelastic X-ray and neutron scattering, and density functional theory calculations. Using complementary M\"ossbauer and nuclear forward scattering we determine the 99Ru magnetic hyperfine splitting to be negligible. Inelastic X-ray and neutron scattering derived lattice dynamics of RuO2 are compared to density functional theory calculations of varying flavors. Comparisons among theory with experiments indicate that electronic correlations, rather than magnetic order, are key in describing the lattice dynamics.
@article{arxiv.2505.03250,
title = {Constraints on magnetism and correlations in RuO$_2$ from lattice dynamics and M\"ossbauer spectroscopy},
author = {George Yumnam and Parul R. Raghuvanshi and John D. Budai and Dipanshu Bansal and Lars Bocklage and Douglas Abernathy and Yongqiang Cheng and Ayman Said and Igor I. Mazin and Haidong Zhou and Benjamin A. Frandsen and David S. Parker and Lucas R. Lindsay and Valentino R. Cooper and Michael E. Manley and Raphaël P. Hermann},
journal= {arXiv preprint arXiv:2505.03250},
year = {2025}
}