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arXiv · 2607.13745

Aharonov-Casher-induced electric quadrupole of charge-neutral particles

Hojun Lee·Youngjae Jeon·Suik Cheon·Hyun-Woo Lee
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Abstract

For charged particles, their orbital angular momentum (OAM) in solid have a direct magnetic manifestation as an orbital magnetization. For charge-neutral particles, however, the physical manifestation of the OAM in solid remains unclear. Here, we show that a charge-neutral particle carrying a magnetic moment couples to electric-field gradient through the Aharonov-Casher (AC) effect, thereby exhibiting the electric quadrupole in crystalline solids. This AC-induced electric quadrupole (AC-EQ) contains the scalar, toroidal dipole, and reduced quadrupole components, which are conjugate to the divergence, circulation, and shear of the electric field, respectively. As representative examples, we calculate the AC-EQ of magnons in two magnetic systems. In ferromagnetic pyrochlore, Dzyaloshinskii-Moriya interaction (DMI) induces a sizable AC-EQ, whereas in helical Fe langasite the AC-EQ emerges from the helical spin configuration even in the absence of DMI.

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Hojun Lee, Youngjae Jeon, Suik Cheon, Hyun-Woo Lee. 2026-09-16. Aharonov-Casher-induced electric quadrupole of charge-neutral particles. https://arxiv.org/abs/2607.13745

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