Altermagnetic and dipolar splitting of magnons in FeF$_2$

Fuente: arXiv
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Main Authors: Sears, J., Garlea, V. O., Lederman, D., Tranquada, J. M., Zaliznyak, I. A.
Format: Preprint
Published: 2026
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author Sears, J.
Garlea, V. O.
Lederman, D.
Tranquada, J. M.
Zaliznyak, I. A.
author_facet Sears, J.
Garlea, V. O.
Lederman, D.
Tranquada, J. M.
Zaliznyak, I. A.
contents FeF$_2$ is a prototypical rutile antiferromagnet recently proposed as an altermagnet, with a magnetic symmetry that permits spin-split electronic bands and chiral magnons. Using very-high-resolution inelastic neutron scattering on a single crystal of FeF$_2$, we show that the dominant source of magnon splitting is in fact the long-range dipolar interaction rather than altermagnetic exchange terms. At momenta where the dipolar splitting vanishes, we observe additional broadening due to altermagnetic chiral splitting and estimate this splitting to be $\sim$35 $μ$eV. Polarized measurements further reveal that, where dipolar splitting is present, the chiral magnon modes become mixed and the resulting modes are predominantly linearly polarized, with at most a small chiral component. These findings highlight the significant effect of dipolar interactions on magnon chirality, particularly when altermagnetic interactions are weak.
format Preprint
id arxiv_https___arxiv_org_abs_2601_04303
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Altermagnetic and dipolar splitting of magnons in FeF$_2$
Sears, J.
Garlea, V. O.
Lederman, D.
Tranquada, J. M.
Zaliznyak, I. A.
Strongly Correlated Electrons
FeF$_2$ is a prototypical rutile antiferromagnet recently proposed as an altermagnet, with a magnetic symmetry that permits spin-split electronic bands and chiral magnons. Using very-high-resolution inelastic neutron scattering on a single crystal of FeF$_2$, we show that the dominant source of magnon splitting is in fact the long-range dipolar interaction rather than altermagnetic exchange terms. At momenta where the dipolar splitting vanishes, we observe additional broadening due to altermagnetic chiral splitting and estimate this splitting to be $\sim$35 $μ$eV. Polarized measurements further reveal that, where dipolar splitting is present, the chiral magnon modes become mixed and the resulting modes are predominantly linearly polarized, with at most a small chiral component. These findings highlight the significant effect of dipolar interactions on magnon chirality, particularly when altermagnetic interactions are weak.
title Altermagnetic and dipolar splitting of magnons in FeF$_2$
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2601.04303