Dynamic helimagnetism via charged spin current
Abstract
We present a theoretical and numerical study of classical, localized spins coupled to conduction electrons that carry both charge and spin currents, deriving the effective equations of motion from the s-d exchange Hamiltonian. Applied to a periodically arranged one-dimensional spin chain, these equations yield two current-driven helical phases: a static helix stabilized by a pure spin current alone, and a coherently precessing helix that appears once a small charge-current component is added. For a given helical wavenumber, the precession angular frequency ω and the canting ratio Δ toward the hard axis follow analytically from the equations of motion, while the wavenumber qhelix of the precessing helix is selected by a heuristically constructed effective Lagrangian. Direct numerical integration of the same equations of motion reproduces all three observables wherever it yields a coherent helix. The helix chirality is set by a long-range, current-generated Dzyaloshinskii-Moriya (DM)-type coupling rather than an intrinsic DM interaction, so materials without bulk or interfacial DM interactions could also host current-controlled helical order. Because the helical pitch, precession frequency, and canting ratio are all continuously tunable by the current amplitudes, these helices could serve as probes of spin currents.
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BibTeX
@misc{onoda2026dynamic,
title = {{Dynamic helimagnetism via charged spin current}},
author = {Masaru Onoda},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.34927},
eprint = {2610.34927},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.34927},
}
RIS
TY - UNPB
TI - Dynamic helimagnetism via charged spin current
AU - Masaru Onoda
PY - 2026
DA - 2026/10/26
PB - arXiv
DO - 10.48550/arxiv.2610.34927
UR - https://arxiv.org/abs/2610.34927
AB - We present a theoretical and numerical study of classical, localized spins coupled to conduction electrons that carry both charge and spin currents, deriving the effective equations of motion from the s-d exchange Hamiltonian. Applied to a periodically arranged one-dimensional spin chain, these equations yield two current-driven helical phases: a static helix stabilized by a pure spin current alone, and a coherently precessing helix that appears once a small charge-current component is added. For a given helical wavenumber, the precession angular frequency ω and the canting ratio Δ toward the hard axis follow analytically from the equations of motion, while the wavenumber q_helix of the precessing helix is selected by a heuristically constructed effective Lagrangian. Direct numerical integration of the same equations of motion reproduces all three observables wherever it yields a coherent helix. The helix chirality is set by a long-range, current-generated Dzyaloshinskii-Moriya (DM)-type coupling rather than an intrinsic DM interaction, so materials without bulk or interfacial DM interactions could also host current-controlled helical order. Because the helical pitch, precession frequency, and canting ratio are all continuously tunable by the current amplitudes, these helices could serve as probes of spin currents.
ER -