Floquet Engineering of Momentum Gaps in Magnonic Time Crystals: Slow-Drive Amplification and In-Gap Propagation

Paweł Gruszecki; Victor Pacheco-Peña

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arXiv · 2610.32766

Floquet Engineering of Momentum Gaps in Magnonic Time Crystals: Slow-Drive Amplification and In-Gap Propagation

Paweł Gruszecki·Victor Pacheco-Peña

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Abstract

Photonic time crystals host momentum gaps in which waves grow exponentially but cannot propagate. We establish their magnonic counterpart in a thin film with periodically switched anisotropy, deriving its Floquet band structure and confirming it micromagnetically. Gaps require a precession-ellipticity contrast. The waveform controls high-order gaps: a single 1~GHz switching drive amplifies a comb of spin-wave bands, from 2.5 to 4.5~GHz, above Gilbert losses even with smoothed edges, unlike sinusoidal modulation. With the Dzyaloshinskii--Moriya interaction, amplified packets propagate inside the gap while growing.

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Paweł Gruszecki, Victor Pacheco-Peña. 2026-10-23. Floquet Engineering of Momentum Gaps in Magnonic Time Crystals: Slow-Drive Amplification and In-Gap Propagation. https://arxiv.org/abs/2610.32766

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