Speaker
Description
The emerging field of altermagnetism combines the merits of both ferromagnets and antiferromagnets, which, until recently, were thought to be incompatible. Consequently, altermagnets exhibit phenomena unmatched by either of these two traditional magnetic phases [1]. Despite the tremendous interest in this novel magnetic phase, the possible relation of altermagnetism to topology has been discussed in only a few cases. Before addressing the role of topology, it is first necessary to examine the role of orbital angular momentum (OAM) in topologically trivial systems. Overall, experimental investigations of the OAM character in altermagnets are of fundamental importance, as they provide essential insights into the underlying wavefunction character of altermagnets and, owing to the topological robustness of their subset - Weyl altermagnets - open avenues for applications in electronic and spintronic devices. We will first introduce the role of OAM and Berry curvature in topologically non-trivial systems. Consequently, we will foreshadow how dichroic techniques can be used to address these initial state wavefunction properties. More broadly, we will discuss OAM in both non-centrosymmetric [2-4] and inversion-symmetric [5] systems with a focus on the implications of OAM occurrence in altermagnetic systems.
Acknowledgements
J.S. would like to thank the QM4ST project with Reg. No. CZ.02.01.01/00/22 008/0004572,cofounded by the ERDF as part of the MŠMT.
References
[1] J. Krempaský et al., “Altermagnetic lifting of Kramers spin degeneracy,” Nature, vol. 626, no. 7999. Springer Science and Business Media LLC, pp. 517–522, Feb. 14, 2024. https://doi.org/10.1038/s41586-023-06907-7
[2] J. Schusser et al., “Assessing Nontrivial Topology in Weyl Semimetals by Dichroic Photoemission,” Physical Review Letters, vol. 129, no. 24. American Physical Society (APS), Dec. 09, 2022. https://doi.org/10.1103/physrevlett.129.246404
[3] J. Schusser et al., “Towards robust dichroism in angle-resolved photoemission,” Communications Physics, vol. 7, no. 1. Springer Science and Business Media LLC, Aug. 08, 2024. https://doi.org/10.1038/s42005-024-01762-y
[4] T. Figgemeier et al., “Imaging Orbital Vortex Lines in Three-Dimensional Momentum Space,” Physical Review X, vol. 15, no. 1. American Physical Society (APS), Feb. 13, 2025. https://doi.org/10.1103/physrevx.15.011032
[5] I. Sidilkover et al., „Reexamining circular dichroism in photoemission from a topological insulator“, in preparation.
