Vibrational dynamics of a two-dimensional microgranular crystal
Name
PhysRevB.96.024303.pdf
Size
625.01 KB
Format
Adobe PDF
Checksum (MD5)
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Author(s)
Wallen, S. P.
Boechler, N.
Stelling, C.
Retsch, M.
Alvarado-Gil, J. J.
Vega-Flick, Alejandro
Duncan, Ryan Andrew
Nelson, Keith Adam
Maznev, Alexei
Date Issued
July 2017
Journal
Physical Review B
Publisher
American Physical Society
Citation
Vega-Flick, A. et al. "Vibrational dynamics of a two-dimensional microgranular crystal." Physical Review B 96, 2 (July 2017): 024303 © 2017 American Physical Society
Version
Final published version
Abstract
We study the dynamics of an ordered hexagonal monolayer of polystyrene microspheres adhered to a glass substrate coated with a thin aluminum layer. A laser-induced transient grating technique is employed to generate and detect three types of acoustic modes across the entire Brillouin zone in the Γ−K direction: low-frequency contact-based modes of the granular monolayer, high-frequency modes originating from spheroidal vibrations of the microspheres, and surface Rayleigh waves. The dispersion relation of contact-based and spheroidal modes indicates that they are collective modes of the microgranular crystal controlled by particle-particle contacts. We observe a spheroidal resonance splitting caused by the symmetry breaking due to the substrate, as well as an avoided crossing between the Rayleigh and spheroidal modes. The measurements are found to be in agreement with our analytical model.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1103/PhysRevB.96.024303
