Activation of anomalous Hall effect and orbital magnetization by domain walls in altermagnets

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Autori principali: Sorn, Sopheak, Mokrousov, Yuriy
Natura: Preprint
Pubblicazione: 2025
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author Sorn, Sopheak
Mokrousov, Yuriy
author_facet Sorn, Sopheak
Mokrousov, Yuriy
contents Altermagnets are an emerging class of unconventional antiferromagnets, characterized by a Néel ordering that does not break the translation symmetry of the underlying lattice. Depending on the orientation of the Néel vector, the anomalous Hall effect (AHE) may or may not exist. In the so-called pure altermagnets, AHE is forbidden by the magnetic symmetry. Here, we demonstrate that in pure altermagnets, the domain walls can lift the symmetry constraints, thereby activating the AHE and orbital magnetization. Taking a representative example of a rutile-lattice tight-binding minimal model in slab geometry, we use the linear response theory to demonstrate the emergence of the domain wall AHE, finding that it is closely related with the orbital magnetization, while the spin magnetization does not play a significant role. Using Landau theory, we argue that while for a random arrangement of $π$ domain walls, the contributions from the individual domain walls will cancel one another, an external magnetic field will favor domain-wall arrangements with specific chirality giving rise to a net AHE signal. Using group theory, we discuss how these findings can be generalized straightforwardly to certain other classes of altermagnets. Our work reveals a crucial role of the domain walls in the understanding of the Hall transport and orbital magnetism of altermagnets.
format Preprint
id arxiv_https___arxiv_org_abs_2505_15894
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Activation of anomalous Hall effect and orbital magnetization by domain walls in altermagnets
Sorn, Sopheak
Mokrousov, Yuriy
Mesoscale and Nanoscale Physics
Materials Science
Altermagnets are an emerging class of unconventional antiferromagnets, characterized by a Néel ordering that does not break the translation symmetry of the underlying lattice. Depending on the orientation of the Néel vector, the anomalous Hall effect (AHE) may or may not exist. In the so-called pure altermagnets, AHE is forbidden by the magnetic symmetry. Here, we demonstrate that in pure altermagnets, the domain walls can lift the symmetry constraints, thereby activating the AHE and orbital magnetization. Taking a representative example of a rutile-lattice tight-binding minimal model in slab geometry, we use the linear response theory to demonstrate the emergence of the domain wall AHE, finding that it is closely related with the orbital magnetization, while the spin magnetization does not play a significant role. Using Landau theory, we argue that while for a random arrangement of $π$ domain walls, the contributions from the individual domain walls will cancel one another, an external magnetic field will favor domain-wall arrangements with specific chirality giving rise to a net AHE signal. Using group theory, we discuss how these findings can be generalized straightforwardly to certain other classes of altermagnets. Our work reveals a crucial role of the domain walls in the understanding of the Hall transport and orbital magnetism of altermagnets.
title Activation of anomalous Hall effect and orbital magnetization by domain walls in altermagnets
topic Mesoscale and Nanoscale Physics
Materials Science
url https://arxiv.org/abs/2505.15894