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Phase diagram and aggregation dynamics of a monolayer of paramagnetic colloids
Abstract
We have developed a tunable colloidal system and a corresponding simulation model
for studying the phase behavior of particles assembling under the influence of long-range
magnetic interactions. A monolayer of paramagnetic particles is subjected to a spatially
uniform magnetic field with a static perpendicular component and rapidly rotating
in-plane component. The sign and strength of the interactions vary with the tilt angle
$\theta$ of the rotating magnetic field. For a purely in-plane field, $\theta=90^{\circ}$,
interactions are attractive and the experimental results agree well with both equilibrium
and out-of-equilibrium predictions based on a two-body interaction model. For tilt
angles $50^{\circ}\lesssim \theta\lesssim 55^{\circ}$, the two-body interaction gives
a short-range attractive and long-range repulsive (SALR) interaction, which predicts
the formation of equilibrium microphases. In experiments, however, a different type
of assembly is observed. Inclusion of three-body (and higher-order) terms in the model
does not resolve the discrepancy. We thus further characterize the anomalous behavior
by measuring the time-dependent cluster size distribution.
Type
Journal articlePermalink
https://hdl.handle.net/10161/14621Collections
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Show full item recordScholars@Duke
Patrick Charbonneau
Professor of Chemistry
Professor Charbonneau studies soft matter. His work combines theory and simulation
to understand the glass problem, protein crystallization, microphase formation, and colloidal
assembly in external fields.
Joshua Socolar
Professor of Physics
Prof. Socolar is interested in collective behavior in condensed matter and dynamical
systems. His current research interests include:
Limit-periodic structures, quasicrystals, packing problems, and tiling theory;
Self-assembly and phases of designed colloidal particles;
Shear jamming and stick-slip behavior in dry granular materials;
Organization and dynamics of complex networks;
Topological elasticity of mechanical lattices.
Benjamin Yellen
Associate Professor in the Department of Mechanical Engineering and Materials Science
Yellen's group is interested in developing highly parallel mechanisms for controlling
the transport and assembly of ensembles of objects ranging from micron-sized colloidal
particles to single cells. As of 2013, Professor Yellen is active in two main areas
of research:1) Development of single cell analysis tools using magnetic circuits.
The goal of this project is to develop an automated single cell analysis platform
that allows for highly flexible and highly paralle
Alphabetical list of authors with Scholars@Duke profiles.

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