Symmetry classification of magnetic octupole current based on multipole representation theory

Fuente: arXiv
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Autori principali: Takasu, Yuuga, Hayami, Satoru
Natura: Preprint
Pubblicazione: 2025
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author Takasu, Yuuga
Hayami, Satoru
author_facet Takasu, Yuuga
Hayami, Satoru
contents Magnetic octupole (MO) currents have recently attracted significant attention as a driving force for the Neel vector dynamics in d-wave altermagnets, a new class of antiferromagnets that exhibit nonrelativistic spin-split band structures. From a symmetry perspective, the MO includes an axial-dipole component analogous to that of the spin, making it essential to clarify how MO currents differ from spin currents. We here investigate the correspondence between MO conductivities and electronic multipoles, which provide a unified and powerful framework for symmetry analysis. We derive the multipole representation of the rank-five MO conductivity tensor and classify its symmetry-allowed components for all crystallographic point groups, in direct comparison with spin conductivity. We show that time-reversal-even electric-type multipoles give rise to the dissipationless MO current, whereas time-reversal-odd magnetic-type multipoles generate dissipative MO current under an applied electric field. Complementing this macroscopic analysis, the linear-response calculations for a microscopic tight-binding model demonstrate how MO conductivities are activated by symmetry lowering, exemplified by the symmetry reduction from Oh to Th. Our results elucidate the symmetry distinctions between MO currents and spin currents, and provide insights into their experimental identification.
format Preprint
id arxiv_https___arxiv_org_abs_2512_15619
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Symmetry classification of magnetic octupole current based on multipole representation theory
Takasu, Yuuga
Hayami, Satoru
Strongly Correlated Electrons
Magnetic octupole (MO) currents have recently attracted significant attention as a driving force for the Neel vector dynamics in d-wave altermagnets, a new class of antiferromagnets that exhibit nonrelativistic spin-split band structures. From a symmetry perspective, the MO includes an axial-dipole component analogous to that of the spin, making it essential to clarify how MO currents differ from spin currents. We here investigate the correspondence between MO conductivities and electronic multipoles, which provide a unified and powerful framework for symmetry analysis. We derive the multipole representation of the rank-five MO conductivity tensor and classify its symmetry-allowed components for all crystallographic point groups, in direct comparison with spin conductivity. We show that time-reversal-even electric-type multipoles give rise to the dissipationless MO current, whereas time-reversal-odd magnetic-type multipoles generate dissipative MO current under an applied electric field. Complementing this macroscopic analysis, the linear-response calculations for a microscopic tight-binding model demonstrate how MO conductivities are activated by symmetry lowering, exemplified by the symmetry reduction from Oh to Th. Our results elucidate the symmetry distinctions between MO currents and spin currents, and provide insights into their experimental identification.
title Symmetry classification of magnetic octupole current based on multipole representation theory
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2512.15619