Observation of mechanical kink control and generation via acoustic waves

Abstract

Abstract Kinks are localized transitions between topologically distinct ground states and play a central role in systems from condensed matter to cosmology. While acoustic wave packets (here defined as small-amplitude mechanical waves, sometimes referred to as phonons) have been predicted to drive kink motion deterministically, experimental evidence has been elusive, with only stochastic motion from thermal phonons or quasi-static loading observed. This is largely due to the discrete nature of real materials, where the Peierls-Nabarro (PN) barrier hinders controlled phonon-kink interactions. Here, we report experimental observation of acoustic-wave–mediated control and generation of mechanical kinks in a topological metamaterial, which eliminates the PN barrier by supporting a zero-energy kink. We also computationally reveal the dynamics of acoustic wave packet interplay with highly discrete kinks, including long-duration motion and a continuous family of internal modes—features absent in conventional discrete nonlinear systems. Our results enable remote kink control, with potential applications in material stiffness tuning, shape morphing, locomotion, and robust signal transmission.