Electrically driven dynamic three-dimensional solitons in nematic liquid crystals

TL;DR

This paper reports the discovery of electrically driven three-dimensional solitons in nematic liquid crystals, which are localized, particle-like waves that can move rapidly, collide, and are controllable through electric fields.

Contribution

It introduces a new type of self-trapped, propagating solitons in nematic liquid crystals driven by electric fields, demonstrating their dynamics and interactions.

Findings

Solitons propagate at high speeds perpendicular to electric field.

They maintain shape over large distances and survive collisions.

Solitons exhibit particle-wave duality and are topologically equivalent to the uniform state.

Abstract

Electric field induced collective reorientation of nematic molecules placed between two flat parallel electrodes is of importance for both fundamental science and practical applications. This reorientation is either homogeneous over the area of electrodes, as in liquid crystal displays, or periodically modulated, as in the phenomenon called electroconvection1, similar to Rayleigh-B\'enard thermal convection. The question is whether the electric field can produce spatially localized propagating solitons of molecular orientation. Here we demonstrate electrically driven three-dimensional particle-like solitons representing self-trapped waves of oscillating molecular orientation. The solitons propagate with a very high speed perpendicularly to both the electric field and the initial alignment direction. The propulsion is enabled by rapid collective reorientations of the molecules with the frequency of the applied electric field and by lack of fore-aft symmetry. The solitons preserve spatially-confined shapes while moving over distances hundreds of times larger than their size and survive collisions. During collisions, the solitons show repulsions and attractions, depending on the impact parameter. The solitons are topologically equivalent to the uniform state and have no static analogs, thus exhibiting a particle-wave duality. We anticipate the observations to be a starting point for a broad range of studies since the system allows for a precise control over a broad range of parameters that determine the shape, propagation speed, and interactions of the solitons.