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

• Published in: Nature communications Vol. 9; no. 1; pp. 2912 - 10
• Main Authors: Li, Bing-Xiang, Borshch, Volodymyr, Xiao, Rui-Lin, Paladugu, Sathyanarayana, Turiv, Taras, Shiyanovskii, Sergij V., Lavrentovich, Oleg D.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 25.07.2018; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/923/919; 639/766/189; Crystals; Electric fields; Humanities and Social Sciences; Liquid crystals; Molecular chains; multidisciplinary; Nematic crystals; Projectiles; Science; Science (multidisciplinary); Solitary waves; Wave propagation
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-05101-y

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. Solitary waves which maintain their shape have many fascinating physical and mathematical properties. Here the authors observe waves trapped along three spatial dimensions in nematic liquid crystals due to an electric field and show that these director bullets can re-form after collisions.