Structural rearrangement-induced acoustic waves in sheared dusty plasma crystals

Yi-Cheng Zhao^1*, Lin I¹

¹Department of Physics, National Central University, Zhongli, Taiwan

* Presenter:Yi-Cheng Zhao, email:yichengzhao51@gmail.com

When particles in a crystal with ordered structure is disturbed, they vibrate, reorganize, and release energy as acoustic waves. These coherent acoustic waves show how the crystal relaxes and restores order. In this study, we use a two-dimensional dusty plasma crystal as a model system to directly observe these processes. The crystal, composed of charged microparticles suspended in a plasma under low pressure, is subjected to a steady laser shear that drives it into an unsteady state. Under shear, local structural rearrangements occur repeatedly as the lattice accommodates the applied strain. Each rearrangement releases stress and excites coherent acoustic phonons that propagate outward as vortical waves with swirling patterns over multiple length scales. These waves transport energy across the lattice but are scattered or confined at grain boundaries and defects, leading to gradual damping. Our observations demonstrate that even under constant shearing, the crystal relaxes through multiscale vibrational modes, revealing a wave-mediated mechanism for stress redistribution in underdamped solids.

Keywords: Coherent phonon, Dusty plasma, Structural rearrangement