Altermagnetism and Weak Ferromagnetism

Fuente: arXiv
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Autori principali: Solovyev, I. V., Nikolaev, S. A., Tanaka, A.
Natura: Preprint
Pubblicazione: 2025
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author Solovyev, I. V.
Nikolaev, S. A.
Tanaka, A.
author_facet Solovyev, I. V.
Nikolaev, S. A.
Tanaka, A.
contents Using a realistic model relevant to La$_2$CuO$_4$ and other altermagnetic perovskite oxides, we study interrelations between weak ferromagnetism (WF), anomalous Hall effect (AHE), and net orbital magnetization (OM). All of them can be linked to the form of Dzyaloshinskii-Moriya (DM) interactions. Nevertheless, while spin WF is induced by the DM vector components having the same sign in all equivalent bonds, AHE and OM are related to alternating-sign components, which do not contribute to any canting of spins. The microscopic model remains invariant under the symmetry operation $\{ \mathcal{S}|{\bf t} \}$, combining the shift ${\bf t}$ of antiferromagnetically coupled sublattices to each other with the spin flip $\mathcal{S}$. Thus, the band structure remains spin-degenerate, but the time-reversal symmetry is broken, providing a possibility to realize AHE in antiferromagnetic substances. The altermagnetic splitting of bands, breaking the $\{ \mathcal{S}|{\bf t}\}$ symmetry, does not play a major role in the problem. More important is the orthorhombic strain, responsible for finite values of AHE and OM.
format Preprint
id arxiv_https___arxiv_org_abs_2503_23735
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Altermagnetism and Weak Ferromagnetism
Solovyev, I. V.
Nikolaev, S. A.
Tanaka, A.
Materials Science
Strongly Correlated Electrons
Using a realistic model relevant to La$_2$CuO$_4$ and other altermagnetic perovskite oxides, we study interrelations between weak ferromagnetism (WF), anomalous Hall effect (AHE), and net orbital magnetization (OM). All of them can be linked to the form of Dzyaloshinskii-Moriya (DM) interactions. Nevertheless, while spin WF is induced by the DM vector components having the same sign in all equivalent bonds, AHE and OM are related to alternating-sign components, which do not contribute to any canting of spins. The microscopic model remains invariant under the symmetry operation $\{ \mathcal{S}|{\bf t} \}$, combining the shift ${\bf t}$ of antiferromagnetically coupled sublattices to each other with the spin flip $\mathcal{S}$. Thus, the band structure remains spin-degenerate, but the time-reversal symmetry is broken, providing a possibility to realize AHE in antiferromagnetic substances. The altermagnetic splitting of bands, breaking the $\{ \mathcal{S}|{\bf t}\}$ symmetry, does not play a major role in the problem. More important is the orthorhombic strain, responsible for finite values of AHE and OM.
title Altermagnetism and Weak Ferromagnetism
topic Materials Science
Strongly Correlated Electrons
url https://arxiv.org/abs/2503.23735