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MA: Fachverband Magnetismus

MA 21: Phd Focus Session: Altermagnets: Foundations and Experimental Evidence

MA 21.2: Invited Talk

Wednesday, March 20, 2024, 10:00–10:30, H 1058

Experimental evidence of time-reversal symmetry breaking in altermagnetic RuO₂ — •O. Fedchenko¹, J. Minar², A. Akashdeep¹, S.W. D’Souza², D. Vasilyev¹, O. Tkach¹, L. Odenbreit¹, Y. Lytvynenko¹, Q. Nguyen³, D. Kutnyakhov⁴, N. Wind⁴, L. Wenthaus⁴, M. Scholz⁴, K. Rossnagel^5,4, M. Hoesch⁴, M. Aeschlimann⁶, B. Stadtmüller¹, M. Kläui¹, G. Schönhense¹, T. Jungwirth^7,8, A. Birk Hellenes¹, G. Jakob¹, L. Šmejkal^1,7, J. Sinova^1,7, and H.-J. Elmers¹ — ¹JGU Mainz, Germany — ²NTC UWB, Czech Republic — ³SLAC, USA — ⁴DESY Hamburg, Germany — ⁵CAU Kiel, Germany — ⁶RPTU, Kaiserslautern, Germany — ⁷Institute of Physics ASCR, Czech Republic — ⁸University of Nottingham, UK

Our experimental study focuses on epitaxial RuO₂, the material of the altermagnetic (AM) class. This class has been predicted to combine properties of ferromagnets (FMs) and antiferromagnets (AFMs). Thus, like AFMs, AMs exhibit compensated magnetic order, and moreover, like FMs, they promote strong spin polarization in the band structure [1]. The corresponding unconventional mechanism is the time-reversal symmetry breaking without magnetization − the primary signature of AMs. Using time-of-flight momentum microscopy, we have spectroscopically measured the key signature of the AM phase, i.e. a magnetic circular dichroism (MCD), for the collinear compensated altermagnet RuO₂ [2].

[1] L. Šmejkal et al., Phys. Rev. X 12, 011028 (2022).

[2] O. Fedchenko et al., arXiv 2306.02170v1 (2023).

Keywords: Altermagnetism; Time-reversal symmetry breaking; RuO2