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Main Authors: Lee, Seungho, Kim, Se Kwon
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2506.16818
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author Lee, Seungho
Kim, Se Kwon
author_facet Lee, Seungho
Kim, Se Kwon
contents We derive an effective field theory for a noncollinear altermagnet and magnons on top of the noncollinear ground state from an altermagnetic Heisenberg model. We obtain the ground-state phase diagram, revealing a noncollinear phase and four distinct collinear phases. The ground state of the noncollinear phase fully breaks the spin rotational symmetry, while the ground state of the collinear phases possesses unbroken $\mathrm{SO}(2)$ symmetry. The resulting effective field theory for the noncollinear phase is an $\mathrm{SO}(3)$ sigma model in which the magnonic excitation has three independent degrees of freedom and exhibits the $d$-wave-like anisotropic linear dispersion. We also discuss possible topological solitons, including $\mathbb{Z}_2$ vortices.
format Preprint
id arxiv_https___arxiv_org_abs_2506_16818
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Effective Field Theory of a Noncollinear Altermagnet
Lee, Seungho
Kim, Se Kwon
Mesoscale and Nanoscale Physics
We derive an effective field theory for a noncollinear altermagnet and magnons on top of the noncollinear ground state from an altermagnetic Heisenberg model. We obtain the ground-state phase diagram, revealing a noncollinear phase and four distinct collinear phases. The ground state of the noncollinear phase fully breaks the spin rotational symmetry, while the ground state of the collinear phases possesses unbroken $\mathrm{SO}(2)$ symmetry. The resulting effective field theory for the noncollinear phase is an $\mathrm{SO}(3)$ sigma model in which the magnonic excitation has three independent degrees of freedom and exhibits the $d$-wave-like anisotropic linear dispersion. We also discuss possible topological solitons, including $\mathbb{Z}_2$ vortices.
title Effective Field Theory of a Noncollinear Altermagnet
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2506.16818