Cross-talk between topological defects in different fields revealed by nematic microfluidics [Applied Physical Sciences]
Topological defects are singularities in material fields that play a vital role across a range of systems: from cosmic microwave
background polarization to superconductors and biological materials. Although topological defects and their mutual interactions
have been extensively studied, little is known about the interplay between defects in different fields—especially when they
coevolve—within the same physical system. Here, using nematic microfluidics, we study the cross-talk of topological defects
in two different material fields—the velocity field and the molecular orientational field. Specifically, we generate hydrodynamic
stagnation points of different topological charges at the center of star-shaped microfluidic junctions, which then interact
with emergent topological defects in the orientational field of the nematic director. We combine experiments and analytical
and numerical calculations to show that a hydrodynamic singularity of a given topological charge can nucleate a nematic defect
of equal topological charge and corroborate this by creating
−1,
−2, and
−3 topological defects in four-, six-, and eight-arm junctions. Our work is an attempt toward understanding materials that are
governed by distinctly multifield topology, where disparate topology-carrying fields are coupled and concertedly determine
the material properties and response.
Publisher URL: http://feedproxy.google.com/~r/Pnas-RssFeedOfEarlyEditionArticles/~3/WVmB-pMnLq4/1702777114.short
DOI: 10.1073/pnas.1702777114
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