# Observation of mechanical kink control and generation via acoustic waves

## TL;DR

The paper demonstrates how acoustic waves can control and generate mechanical kinks in a special metamaterial, enabling new applications in material science.

## Contribution

The study experimentally observes acoustic wave-mediated control of zero-energy mechanical kinks in a topological metamaterial.

## Key findings

- Acoustic waves enable deterministic control and generation of mechanical kinks in a topological metamaterial.
- The system supports long-duration kink motion and internal modes absent in conventional discrete systems.
- This approach eliminates the Peierls-Nabarro barrier, allowing for remote kink manipulation.

## 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.

Kinks are topological solitons and central to many physical systems. Here, the authors experimentally demonstrate control and generation of zero-energy kinks in a topological mechanical metamaterial via acoustic waves and numerically show rich acoustic-wavekink dynamics in highly discrete systems.