Dynamic Magnonic Crystals Based on Spatiotemporal Plasmon Excitation.

Metamaterials, designed to exhibit properties beyond those found in nature, enable unprecedented control over physical phenomena through flexible band structure engineering. This work introduces a hybrid magnonic-plasmonic metamaterial that allows spatiotemporal manipulation of spin-wave transport at micrometer scales and sub-microsecond timescales. The system integrates a plasmonic metamaterial, comprising Au nanodisk arrays arranged in a 1D periodic stripe pattern, with a low-damping yttrium iron garnet (YIG) film as the spin-wave transport medium. Short laser pulses (100-500 ns) excite surface lattice resonances (SLRs) in the plasmonic stripes, inducing thermoplasmonic heating and generating a striped temperature profile. This dynamic thermal modulation periodically alters the YIG film's saturation magnetization, forming a laser-controlled magnonic crystal. Time-resolved propagating spin-wave spectroscopy reveals tunable bandgaps and minibands arising from Bragg reflection. By adjusting the plasmonic stripe pattern, laser pulse duration, or power, this system enables precise control over spin-wave transport, paving the way for reconfigurable wave-based computing devices.