Rotational Doppler Effect and Helimagnon Frequency Comb in Sliding Magnetic Spirals
Abstract
Collective spin motion can reshape magnon spectra by providing a dynamical magnetic background. Magnetic spirals offer a particularly clean setting, as they simultaneously host propagating helimagnons and a gapless Goldstone mode, i.e., the sliding of the spiral. Here, we show that once a helimagnon is excited and the spiral slides, the motion, which rotates the local spin frame, produces a thresholdless rotational Doppler shift of the helimagnon spectrum, with even winding for the linear mode and odd winding for its second harmonic. Stronger excitation generates one finite-momentum phason. Mixing of that phason with the helimagnon produces a helimagnon frequency comb only inside a finite driving window, spaced by the phason frequency fixed by the spiral length rather than by the sliding rate. These two scales are separable in a microwave experiment: the Doppler offset tracks the sliding velocity, whereas the comb spacing scales inversely with the length of the spiral.
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BibTeX
@misc{liu2026rotational,
title = {{Rotational Doppler Effect and Helimagnon Frequency Comb in Sliding Magnetic Spirals}},
author = {Yang Liu and Jie Liu and Tianci Gong and Zhaozhuo Zeng and Xiaoping Gao and Kai Chang and Peng Yan},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.08873},
eprint = {2611.08873},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.08873},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Rotational Doppler Effect and Helimagnon Frequency Comb in Sliding Magnetic Spirals
AU - Yang Liu
AU - Jie Liu
AU - Tianci Gong
AU - Zhaozhuo Zeng
AU - Xiaoping Gao
AU - Kai Chang
AU - Peng Yan
PY - 2026
DA - 2026/11/06
PB - arXiv
DO - 10.48550/arxiv.2611.08873
UR - https://arxiv.org/abs/2611.08873
AB - Collective spin motion can reshape magnon spectra by providing a dynamical magnetic background. Magnetic spirals offer a particularly clean setting, as they simultaneously host propagating helimagnons and a gapless Goldstone mode, i.e., the sliding of the spiral. Here, we show that once a helimagnon is excited and the spiral slides, the motion, which rotates the local spin frame, produces a thresholdless rotational Doppler shift of the helimagnon spectrum, with even winding for the linear mode and odd winding for its second harmonic. Stronger excitation generates one finite-momentum phason. Mixing of that phason with the helimagnon produces a helimagnon frequency comb only inside a finite driving window, spaced by the phason frequency fixed by the spiral length rather than by the sliding rate. These two scales are separable in a microwave experiment: the Doppler offset tracks the sliding velocity, whereas the comb spacing scales inversely with the length of the spiral.
ER -