Spatio-temporal Visualization of Individual Phonon and Magnon Propagation in a Magnetic thin Film

Magnon–surface strain interactions have garnered significant attention for their potential to enable long–distance magnetic information transfer in metallic systems [1]. Surface acoustic waves (SAWs) present a promising platform for strain-driven spin manipulation [2], with their long-range coupling behavior confirmed by imaging the reduction in surface vibration amplitude [3]. However, the spatiotemporal dynamics of such coupled magnon-phonon systems remain largely unexplored. Here, we address this gap by visualizing the spatiotemporal evolution of both an optically excited magnon and a surface phonon—generated by an optically induced SAW—under the same excitation conditions [4]. By capturing a wide temporal window (~5 ns) with high resolution (~4 ps), we construct “movies” of ultrafast magnon and phonon propagation. This capability paves the way for a more detailed investigation of the coupling dynamics between magnons and phonons.