Noncollinear Magnetic Multipoles in Collinear Altermagnets

Fuente: arXiv
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Main Authors: Buiarelli, Luca, Fernandes, Rafael M., Birol, Turan
Format: Preprint
Published: 2025
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author Buiarelli, Luca
Fernandes, Rafael M.
Birol, Turan
author_facet Buiarelli, Luca
Fernandes, Rafael M.
Birol, Turan
contents Altermagnets host an array of magnetic multipoles, which are often visualized and studied in the reciprocal space. In the real space, the relative phase of the multipoles of the spin-density around atoms determines whether a system is an altermagnet or a conventional antiferromagnet. In this study, we approach these real space multipoles in altermagnets using a combination of first principles calculations and group theory. We show that even in collinear magnets, the local spin density is necessarily noncollinear due to spin-orbit coupling. Moreover, the noncollinear contributions often provide a more direct illustration of the magnetic multipolar character of altermagnetism than the collinear contribution, which is dominated by the dipolar term. Our first principles calculations also show that 32-poles, in addition to the octupoles, can be visible in spin-density of d-wave altermagnets, and they must be taken into account in discussions of the macroscopic response. Finally, we elucidate the interplay between magnetism and subtle crystal structural distortions in perovskite altermagnets, which provide a fertile playground for studying phase transitions between antiferromagnetic and altermagnetic phases.
format Preprint
id arxiv_https___arxiv_org_abs_2509_23117
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Noncollinear Magnetic Multipoles in Collinear Altermagnets
Buiarelli, Luca
Fernandes, Rafael M.
Birol, Turan
Materials Science
Altermagnets host an array of magnetic multipoles, which are often visualized and studied in the reciprocal space. In the real space, the relative phase of the multipoles of the spin-density around atoms determines whether a system is an altermagnet or a conventional antiferromagnet. In this study, we approach these real space multipoles in altermagnets using a combination of first principles calculations and group theory. We show that even in collinear magnets, the local spin density is necessarily noncollinear due to spin-orbit coupling. Moreover, the noncollinear contributions often provide a more direct illustration of the magnetic multipolar character of altermagnetism than the collinear contribution, which is dominated by the dipolar term. Our first principles calculations also show that 32-poles, in addition to the octupoles, can be visible in spin-density of d-wave altermagnets, and they must be taken into account in discussions of the macroscopic response. Finally, we elucidate the interplay between magnetism and subtle crystal structural distortions in perovskite altermagnets, which provide a fertile playground for studying phase transitions between antiferromagnetic and altermagnetic phases.
title Noncollinear Magnetic Multipoles in Collinear Altermagnets
topic Materials Science
url https://arxiv.org/abs/2509.23117