Structure, Control, and Dynamics of Altermagnetic Textures

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Abstract
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Altermagnets are collinear magnetically ordered phases with zero net magnetization and alternating spin polarization. These emergent materials combine fast magnetic dynamics with large spin band splitting. Both effects arise from strong (non-relativistic) exchange interactions between local magnetic moments and electron spins. I will present a phenomenological theory of alter magnets that describes their unique magnetization dynamics and magnetic textures. Focusing on prototypical d-wave alter magnets such as RuO₂, we can intuitively explain the unique lifted degeneracy of their magnon spectra by the emergence of an effective, sublattice-dependent, anisotropic spin stiffness, which arises naturally from the phenomenological theory. I will discuss asymmetry-based approach to describe alter magnetic textures and dynamics using the alter magnet candidate Mn₅Si₃ as an example. The approach’s key point is an alter magnetic order parameter that formalizes the symmetry of the magnetic atoms’ local environment and enables the alter magnetic behavior to be distilled [1]. I will demonstrate how this concept enables us to reconstruct the equilibrium magnetic structure of Mn₅Si₃ from the field dependences of the anomalous Hall effect [2]–[4]. Finally, I will discuss the spin wave spectra and dynamics of the alter magnetic domain wall, focusing on a comparison between the alter magnetic and antiferromagnetic phases of the material.

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About the Speaker
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Olena V. Gomonay obtained an M.Sc. in condensed matter physics from the Moscow Institute of Physics and Technology (1985), followed by doctoral degrees from the Kurdyumov Institute of Metal Physics, National Academy of Sciences of Ukraine (1992; 2003). She became Associate Professor in 1995 and Professor in 2002 at the National Technical University of Ukraine – Kyiv Polytechnic Institute. Since 2015, she has been a member of the INSPIRE-SPICE Group at Johannes Gutenberg University Mainz. Her research spans antiferromagnetic and alter magnetic spintronics, magnetism theory, magnetoelasticity, and quantum optics.