Scaling and spontaneous symmetry restoring of topological defect dynamics in liquid crystal

Abstract

Topological defects -- locations of local mismatch of order -- are a universal concept playing important roles in diverse systems studied in physics and beyond, including the universe, various condensed matter systems, and recently, even life phenomena. Among these, liquid crystal has been a platform for studying topological defects via visualization, yet it has been a challenge to resolve three-dimensional structures of dynamically evolving singular topological defects. Here, we report a direct confocal observation of nematic liquid crystalline defect lines, called disclinations, relaxing from an electrically driven turbulent state. We focus in particular on reconnections, characteristic of such line defects. We find a scaling law for in-plane reconnection events, by which the distance between reconnecting disclinations decreases by the square root of time to the reconnection. Moreover, we show that apparently asymmetric dynamics of reconnecting disclinations is actually symmetric in a comoving frame, in marked contrast to the two-dimensional counterpart whose asymmetry is established. We argue, with experimental supports, that this is because of energetically favorable symmetric twist configurations that disclinations take spontaneously, thanks to the topology that allows for rotation of the winding axis. Our work illustrates a general mechanism of such spontaneous symmetry restoring that may apply beyond liquid crystal, which can take place if topologically distinct asymmetric defects in lower dimensions become homeomorphic in higher dimensions and if the symmetric intermediate is energetically favorable.

7+11 pages, 4+7 figures, 4 videos

References in corpus (7)

• Characterization of reconnecting vortices in superfluid helium
• Reconfigurable interactions and three-dimensional patterning of colloidal particles and defects in lamellar soft media
• Geometry and mechanics of disclination lines in 3D nematic liquid crystals
• Morphology of active deformable 3D droplets
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• Tilt-induced polar order and topological defects in growing bacterial populations
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Cited by in corpus (4)

• Kinematics and dynamics of disclination lines in three-dimensional nematics
• A computational study of nematic core structure and disclination interactions in elastically anisotropic nematics
• Approach and rotation of reconnecting topological defect lines in liquid crystal
• Defect Interactions Through Periodic Boundaries in Two-Dimensional $p$-atics