Vibrational dynamics of a two-dimensional microgranular crystal

A. Vega-Flick, R. A. Duncan, S. P. Wallen, N. Boechler, C. Stelling, M. Retsch, J. J. Alvarado-Gil, K. A. Nelson, and A. A. Maznev
Phys. Rev. B 96, 024303 – Published 24 July 2017

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 ΓK 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.

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  • Received 23 March 2017
  • Revised 27 May 2017

DOI:https://doi.org/10.1103/PhysRevB.96.024303

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

A. Vega-Flick1,2,*, R. A. Duncan1, S. P. Wallen3, N. Boechler3, C. Stelling4, M. Retsch4, J. J. Alvarado-Gil2, K. A. Nelson1, and A. A. Maznev1,†

  • 1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
  • 2Applied Physics Department, CINVESTAV-Unidad Mérida, Carretera Antigua a Progreso Km 6, Cordemex, Mérida, Yucatán 97310, México
  • 3Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195, USA
  • 4Physical Chemistry, University of Bayreuth, Universitätsstrasse 30, 95447 Bayreuth, Germany

  • *avegaflick@gmail.com
  • maznev@mit.edu

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Issue

Vol. 96, Iss. 2 — 1 July 2017

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