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MA: Fachverband Magnetismus
MA 13: Altermagnets II
MA 13.8: Vortrag
Dienstag, 18. März 2025, 11:30–11:45, H20
Crystal structure and absence of magnetic order in single crystalline RuO2 — •Lara Kiefer1, Felix Wirth1, Alexandre Bertin1, Petra Becker2, Ladislav Bohatý2, Karin Schmalzl3, Anne Stunault4, José Alberto Rodríguez-Velemazan4, Oscar Fabelo4, and Markus Braden1 — 1II. Physic. Inst., Univ. Cologne, Germany — 2Inst. Geology a. Mineralogie, Univ. Cologne, Germany — 3Fz Jülich, Grenoble, France — 4ILL, Grenoble, France
The recent report of antiferromagnetic order above room temperature in RuO2 and its identification as an altermagnetic state boosted research on the material [1,2]. However, muon and neutron experiments, along with DFT calculations, recently questioned the existence of magnetic order in RuO2 and suggested that it only occurs in the presence of vacancies [3-4]. We conducted polarized and unpolarized neutron diffraction experiments on RuO2 crystals, which were characterized by magnetization, EDX, electrical conductance, and XRD measurements [5]. We did not confirm the proposed structural distortion in our crystals down to 2K. Ruthenium vacancies were below a few percent in our crystals. Polarized neutron experiments did not show magnetic Bragg reflections for the proposed k→=(0,0,0) [2]. Even a smaller ordered moment would have yielded significant intensities. Thus, this antiferromagnetic order is ruled out in our stoichiometric crystals [5]. [1] L. Ŝmejkal et al., 2022, Phys. Rev. X 12(3), 031042.[2] T. Berjilin et al., 2017, Phys. Rev. Lett. 118, 077201.[3] A. Smolyanyuk et al., 2024, Phys. Rev. B. 109, 134424. [4] P. Keßler et al., 2024, npj Spintronics 2, 50. [5] L. Kiefer et al., 2024, arXiv, 2410.05850.
Keywords: RuO2; Polarised neutron diffraction; Single crystal diffraction; Altermagnetism; Crystal structure