Electrically driven three-dimensional solitary waves as director bullets in nematic liquid crystals

Bing-Xiang Li,Taras Turiv,Oleg D Lavrentovich,Sergij V Shiyanovskii,Sathyanarayana Paladugu,Rui-Lin Xiao,Volodymyr Borshch

doi:10.1038/s41467-018-05101-y

Bing-Xiang Li, Taras Turiv + Show 5 more

Open Access

https://doi.org/10.1038/s41467-018-05101-y

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Abstract

Electric field-induced collective reorientation of nematic molecules is of importance for fundamental science and practical applications. This reorientation is either homogeneous over the area of electrodes, as in displays, or periodically modulated, as in electroconvection. The question is whether spatially localized three-dimensional solitary waves of molecular reorientation could be created. Here we demonstrate that the electric field can produce particle-like propagating solitary waves representing self-trapped “bullets” of oscillating molecular director. These director bullets lack fore-aft symmetry and move with very high speed perpendicularly to the electric field and to the initial alignment direction. The bullets are true solitons that preserve spatially confined shapes and survive collisions. The solitons are topologically equivalent to the uniform state and have no static analogs, thus exhibiting a particle–wave duality. Their shape, speed, and interactions depend strongly on the material parameters, which opens the door for a broad range of future studies.

Highlights

Electric field-induced collective reorientation of nematic molecules is of importance for fundamental science and practical applications
When a static or low-frequency (
We present an experimental realization of “director bullets”, representing 3D solitary waves with dual particle–wave character that propagate through a slab of a uniformly aligned nematic liquid crystal, being powered by an alternating current (AC) electric field

Summary

Introduction

Electric field-induced collective reorientation of nematic molecules is of importance for fundamental science and practical applications. We demonstrate that the electric field can produce particle-like propagating solitary waves representing self-trapped “bullets” of oscillating molecular director These director bullets lack fore-aft symmetry and move with very high speed perpendicularly to the electric field and to the initial alignment direction. Studies of spatially restricted director perturbations, termed as solitons or, more properly, topological configurations[5], in nematics started about 50 years ago with the discussion of static linear and planar solitons produced by the magnetic or electric fields[6]. These solitons form when the external field aligns the director parallel to itself because of dielectric or diamagnetic anisotropy. The bullets are topologically equivalent to a uniform state (i.e., the director field can be smoothly transformed into a uniform state) and have no static analogs

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