Regensburg 2025 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 13: Altermagnets II
MA 13.13: Vortrag
Dienstag, 18. März 2025, 12:45–13:00, H20
Quasi-symmetry Constrained Spin Ferromagnetism in Altermagnets — Mercè Roig1,2, Yue Yu2, Rune C. Ekman1, •Andreas Kreisel1, Brian M. Andersen1, and Daniel F. Agterberg2 — 1Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark — 2Department of Physics, University of Wisconsin Milwaukee, Milwaukee, Wisconsin 53201, USA
Altermagnets break time-reversal symmetry and their spin-orbit coupling (SOC) allow for an anomalous Hall effect (AHE) that depends on the direction of the Néel ordering vector. AHE and ferromagnetic spin moment share the same symmetry and hence are usually proportional. However, density functional theory (DFT) calculations find that the AHE exists with negligible ferromagnetic spin moment for some compounds, whereas it reaches sizable values for other altermagnets. By examining realistic minimal models for altermagnetism in which the DFT phenomenology is captured, we uncover a general SOC-enabled quasi-symmetry that provides a natural explanation for the amplitude of the ferromagnetic spin moment across the vast range of different altermagnetic materials. Additionally, we derive analytic expressions for the magnetic anisotropy energy, providing a simple means to identify the preferred altermagnetic Néel vector orientation for altermagnets.
Keywords: Altermagnets; anomalous Hall effect; Ferromagnetism