Gyrotropic magnetic effect in metallic chiral magnets

Fuente: arXiv
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Autores principales: Paul, Nisarga, Park, Takamori, Han, Jung Hoon, Balents, Leon
Formato: Preprint
Publicado: 2025
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author Paul, Nisarga
Park, Takamori
Han, Jung Hoon
Balents, Leon
author_facet Paul, Nisarga
Park, Takamori
Han, Jung Hoon
Balents, Leon
contents We study the gyrotropic magnetic effect (GME), the low-frequency limit of optical gyrotropy, in metals and semimetals coupled to chiral spin textures. In these systems, the chiral spin texture which lacks inversion symmetry can imprint itself upon the electronic structure through Hund's coupling, leading to novel low-frequency optical activity. Using perturbation theory and numerical diagonalization of both relativistic and non-relativistic models of conduction electrons coupled to spin textures, we analyze how the GME manifests in both single-$q$ and multi-$q$ textures. Analytical expressions for the rotatory power are derived in terms of universal scaling functions. Estimates based on realistic material parameters reveal an experimentally viable range of values for the rotatory power. The GME arises from the orbital and spin magnetic moments of conduction electrons, with the orbital part closely tied to Berry curvature and playing a significant role in relativistic metals but not so in non-relativistic metals where there is no inherent Berry curvature. The spin contribution to the GME can be significant in non-relativistic metals with a large Fermi energy. Our work establishes the GME as a sensitive probe of magnetic chirality and symmetry breaking in metallic chiral magnets.
format Preprint
id arxiv_https___arxiv_org_abs_2504_20153
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Gyrotropic magnetic effect in metallic chiral magnets
Paul, Nisarga
Park, Takamori
Han, Jung Hoon
Balents, Leon
Mesoscale and Nanoscale Physics
We study the gyrotropic magnetic effect (GME), the low-frequency limit of optical gyrotropy, in metals and semimetals coupled to chiral spin textures. In these systems, the chiral spin texture which lacks inversion symmetry can imprint itself upon the electronic structure through Hund's coupling, leading to novel low-frequency optical activity. Using perturbation theory and numerical diagonalization of both relativistic and non-relativistic models of conduction electrons coupled to spin textures, we analyze how the GME manifests in both single-$q$ and multi-$q$ textures. Analytical expressions for the rotatory power are derived in terms of universal scaling functions. Estimates based on realistic material parameters reveal an experimentally viable range of values for the rotatory power. The GME arises from the orbital and spin magnetic moments of conduction electrons, with the orbital part closely tied to Berry curvature and playing a significant role in relativistic metals but not so in non-relativistic metals where there is no inherent Berry curvature. The spin contribution to the GME can be significant in non-relativistic metals with a large Fermi energy. Our work establishes the GME as a sensitive probe of magnetic chirality and symmetry breaking in metallic chiral magnets.
title Gyrotropic magnetic effect in metallic chiral magnets
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2504.20153