Movie S3.

Dynamic recoil of elasto-magnetic metamaterials with Q=1, w₀=0.14L₀, and a₀=0.17b₀. Open-toclosed phase transitions are observed as recoiling is initiated by a trigger at time t=0 ms. The propagations of the phase transitions, superposed to the dynamic recoil, significantly accelerate the recoil velocity. The propagation of the dynamic recoil and the phase transitions travel with different wave speeds governed by the mechanical and magnetic interaction.