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Nonequilibrium Interface and Surface Dynamics 2007
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2D Self-Assembling Systems Far from
Equilibrium
CSIC Building (#406),
Seminar Room 4122.
Directions: home.cscamm.umd.edu/directions
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2D Self-Assembling Systems Far from Equilibrium
Professor
Vivek Shenoy
Brown University
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Abstract:
It is well known that long-range elastic,
electrostatic, or magnetic interactions can induce
the spontaneous formation of 2D periodic patterns in
two-phase systems. In many cases, the features have
nanoscale dimensions, making them of interest for
sub-lithographic surface templating. For
self-assembled patterns in equilibrium, the
characteristic feature sizes can be directly related
to surface thermodynamic parameters, which can then
be extracted from experiments in material systems
that are easily equilibrated. However, in many
cases, interplay of crystalline anisotropy and
long-range interactions can give rise to complex
energy landscapes that make equilibration
practically impossible. Here we study the growth of
isolated stress domains far from equilibrium using
in situ electron microscopy. While small domains
always adopt compact shapes, depending on the growth
conditions, large domains either develop serrated
edges or evolve into ramified metastable
configurations, both of which are not predicted by
existing theoretical models. By comparing the
recorded shapes with dynamic growth simulations, we
gain a quantitative understanding of how the domain
shapes fall out of equilibrium and why metastability
occurs in this system. We then show that the
thermodynamic parameters that govern self assembly
can be determined by analyzing shapes that the
domains adopt as they grow in size. In addition, we
have identified a generic metastable domain
configuration that will be adopted by essentially
any self-assembling system at large domain size. |
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