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Where are the Hedgehogs in Nematics?

Mark Hindmarsh
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Abstract

In experiments which take a liquid crystal rapidly from the isotropic to the nematic phase, a dense tangle of defects is formed. In nematics, there are in principle both line and point defects (``hedgehogs''), but no point defects are observed until the defect network has coarsened appreciably. In this letter the expected density of point defects is shown to be extremely low, approximately $10^{-8}$ per initially correlated domain, as result of the topology (specifically, the homology) of the order parameter space.

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Mark Hindmarsh. 1995-01-09. Where are the Hedgehogs in Nematics?. https://doi.org/10.1103/physrevlett.75.2502

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