Complex Contact-Based Dynamics of Microsphere Monolayers Revealed by Resonant Attenuation of Surface Acoustic Waves

• DOI: 10.1103/physrevlett.116.198001
• Publication Date: 2016-05-11T22:08:34Z
• Authors: M. Hiraiwa; M. Abi Ghanem; S. P. Wallen; A. Khanolkar; A. A. Maznev; N. Boechler
• Keywords: Particle (ecology); Acoustic attenuation; Acoustic resonance

Contact-based vibrations play an essential role in the dynamics of granular materials. Significant insights into vibrational have previously been obtained with reduced-dimensional systems containing macroscale particles. We study contact-based a two-dimensional monolayer micron-sized spheres on solid substrate that forms microscale crystal. Measurements resonant attenuation laser-generated surface acoustic waves reveal three collective modes involve displacements and rotations microspheres, as well interparticle particle-substrate interactions. To identify modes, we tune stiffness, which shifts frequency horizontal-rotational resonances while leaving vertical resonance unaffected. From measured contact frequencies determine both stiffnesses find former is order magnitude larger than latter. This paves way for investigating complex crystals yields new approach to studying micro- nanoscale mechanics multiparticle networks.