Structure and dynamics of self-assembling colloidal monolayers in oscillating magnetic fields

Alison E. Koser, Nathan C. Keim, Paulo E. Arratia

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Many fascinating phenomena such as large-scale collective flows, enhanced fluid mixing, and pattern formation have been observed in so-called active fluids, which are composed of particles that can absorb energy and dissipate it into the fluid medium. For active particles immersed in liquids, fluid-mediated viscous stresses can play an important role on the emergence of collective behavior. Here, we experimentally investigate their role in the dynamics of self-assembling magnetically driven colloidal particles which can rapidly form organized hexagonal structures. We find that viscous stresses reduce hexagonal ordering, generate smaller clusters, and significantly decrease the rate of cluster formation, all while holding the system at constant number density. Furthermore, we show that time and length scales of cluster formation depend on the Mason number (Mn), or ratio of viscous to magnetic forces, scaling as tâ̂Mn and Lâ̂Mn-1/2. Our results suggest that viscous stresses hinder collective behavior in a self-assembling colloidal system.

Original languageEnglish (US)
Article number062304
JournalPhysical Review E - Statistical, Nonlinear, and Soft Matter Physics
Issue number6
StatePublished - Dec 10 2013
Externally publishedYes

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Statistics and Probability
  • Condensed Matter Physics


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