Orbital magnetic octupole in crystalline solids and anomalous Hall response to a nonuniform electric field

Fuente: arXiv
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Main Authors: Sato, Takumi, Hayami, Satoru
Format: Preprint
Published: 2025
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author Sato, Takumi
Hayami, Satoru
author_facet Sato, Takumi
Hayami, Satoru
contents Magnetic multipole moments beyond dipoles have emerged as key descriptors of unconventional electromagnetic responses in crystalline solids. However, a gauge-invariant bulk expression for orbital magnetic multipole moments has remained elusive, hindering a unified understanding of their physical consequences. Here we formulate a gauge-invariant expression for the orbital magnetic octupole moment in periodic crystals and investigate its behavior in a minimal model of $d$-wave altermagnets. We show that the orbital magnetic octupole is naturally linked to a higher-rank Hall response induced by spatially nonuniform electric fields, leading to a generalized Středa-type relation. Finally, we demonstrate that such a Hall response can arise even when symmetry forbids the conventional anomalous Hall effect against uniform electric fields, thereby providing an illustrative response characteristic to altermagnets.
format Preprint
id arxiv_https___arxiv_org_abs_2512_24269
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Orbital magnetic octupole in crystalline solids and anomalous Hall response to a nonuniform electric field
Sato, Takumi
Hayami, Satoru
Mesoscale and Nanoscale Physics
Magnetic multipole moments beyond dipoles have emerged as key descriptors of unconventional electromagnetic responses in crystalline solids. However, a gauge-invariant bulk expression for orbital magnetic multipole moments has remained elusive, hindering a unified understanding of their physical consequences. Here we formulate a gauge-invariant expression for the orbital magnetic octupole moment in periodic crystals and investigate its behavior in a minimal model of $d$-wave altermagnets. We show that the orbital magnetic octupole is naturally linked to a higher-rank Hall response induced by spatially nonuniform electric fields, leading to a generalized Středa-type relation. Finally, we demonstrate that such a Hall response can arise even when symmetry forbids the conventional anomalous Hall effect against uniform electric fields, thereby providing an illustrative response characteristic to altermagnets.
title Orbital magnetic octupole in crystalline solids and anomalous Hall response to a nonuniform electric field
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2512.24269