Speaker
Description
We provide experimental evidence for the absence of a magnetic moment in bulk RuO$_2$, a candidate altermagnetic material, by using a combination of inelastic neutron and X-ray scattering, Mössbauer spectroscopy, nuclear forward scattering, and density functional theory calculations. The lattice dynamics from our inelastic neutron/x-ray scattering experiments were compared to density functional theory calculated lattice dynamics with various functionals by estimating the dynamic structure factor and the bose-factor corrected dynamic susceptibility. This comparison reveals that the DFT calculated non-magnetic RuO$_2$ structure provides the best description of our inelastic scattering experiments. Using complementary Mössbauer and nuclear forward scattering we also determine the $^{99}$Ru magnetic hyperfine splitting to be negligible, which further substantiates the non-magnetic behavior of RuO$_2$. Our comprehensive analysis indicates that the electronic correlations, rather than magnetic order, are key in describing the lattice dynamics.
Acknowledgement: Research was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division (BES-MSED). A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. The beam time was allocated to ARCS on proposal number IPTS-17267.1. A portion of this research used resources at the Advanced Photon Source, a DOE Office of Science User Facility operated by Argonne National Laboratory.
Reference
Yumnam, G., Raghuvanshi, P.R., Budai, J.D., Bansal, D., Bocklage, L., Abernathy, D., Cheng, Y., Said, A., Mazin, I.I., Zhou, H., Frandsen, B.A., et al. Constraints on magnetism and correlations in RuO$_2$ from lattice dynamics and Mössbauer spectroscopy, arXiv:2505.03250 (2025).
| Topical Area | Hard matter: quantum, electronic, semiconducting materials |
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