Quasi-symmetry Constrained Spin Ferromagnetism in Altermagnets

Fuente: arXiv
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Hauptverfasser: Roig, Mercè, Yu, Yue, Ekman, Rune C., Kreisel, Andreas, Andersen, Brian M., Agterberg, Daniel F.
Format: Preprint
Veröffentlicht: 2024
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author Roig, Mercè
Yu, Yue
Ekman, Rune C.
Kreisel, Andreas
Andersen, Brian M.
Agterberg, Daniel F.
author_facet Roig, Mercè
Yu, Yue
Ekman, Rune C.
Kreisel, Andreas
Andersen, Brian M.
Agterberg, Daniel F.
contents 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. The AHE and the 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, the uniaxial spin space-group, 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 Néel vector orientation for altermagnets.
format Preprint
id arxiv_https___arxiv_org_abs_2412_09338
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Quasi-symmetry Constrained Spin Ferromagnetism in Altermagnets
Roig, Mercè
Yu, Yue
Ekman, Rune C.
Kreisel, Andreas
Andersen, Brian M.
Agterberg, Daniel F.
Strongly Correlated Electrons
Mesoscale and Nanoscale Physics
Materials Science
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. The AHE and the 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, the uniaxial spin space-group, 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 Néel vector orientation for altermagnets.
title Quasi-symmetry Constrained Spin Ferromagnetism in Altermagnets
topic Strongly Correlated Electrons
Mesoscale and Nanoscale Physics
Materials Science
url https://arxiv.org/abs/2412.09338