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SUMMARY:Topological colloids and particle-induced defects in liquid crysta
 ls - Smalyukh\, I (University of Colorado)
DTSTART:20130625T080000Z
DTEND:20130625T084500Z
UID:TALK45899@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:We fabricate colloidal particles with nontrivial surface topol
 ogy\, including colloidal handlebodies\, knots\, links\, Mobius strings\, 
 and Seifert surfaces. When introduced into a nematic liquid crystal with a
  uniform far-field director\, these particles induce three-dimensional dir
 ector fields and topological defects around them. We use director switchin
 g by electric fields\, laser tweezing of defects\, and local photothermal 
 melting of the liquid crystal to promote transformations among many stable
  and metastable particle-induced director configurations and then explore 
 them by means of a direct label-free three-dimensional nonlinear optical i
 maging. This reveals many peculiarities of the interplay between topologie
 s of colloidal surfaces\, director fields\, and defects\, which we find be
 ing in agreement with Gauss-Bonnet and Poincar-Hopf index theorems. The le
 cture will conclude with a brief discussion of how these findings may lay 
 the groundwork for new types of topology-di ctated elastic self-assembly i
 n liquid crystals and experimental study of low-dimensional topology.\n
LOCATION:Centre for Mathematical Sciences\, Meeting Room 2
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