－Generation of controllable particle-like wave－

The so-called nematic liquid crystals (NLC) are key entities for modern technologies, which are widely used in many areas such as liquid crystal displays, lubrication, electric circuit detection, and the like. Meanwhile, they are also known as fundamental platforms to study universal fundamental phenomena, from university to spin systems. In this study, the authors have revealed that time-oscillatory topological waves that carry the wave-particle duality, a new type of solitons, can be stably generated in liquid crystal systems. Furthermore, the authors have shown that changing the amplitude and frequency of the electric field leads to the control of kinetics of the waves, resulting in various intriguing dynamics such as directional propagation, reflection, fractalization, and so on. The result suggests the existence of indeterminate physical problems about the nonequilibrium dynamics in soft matter systems or beyond. The indication is surely important for soliton science, especially for quantum phenomena like skyrmions or hopfions.

In the study, the authors prepared NLC samples with different combinations of dielectric and conductive anisotropies, and mixed a small amount of ionic specie to change the strength of the absolute conductivity. At proper conditions, topological solitons are generated when an electric field is applied. By varying the condition of the applied electric field, the generated solitons start to pack, attract, repel, moving with directionality, reflect. Some of the wave dynamics mimic the counterparts of real particles and some are specific for topological orientational fields. Moreover, the solitons at high voltage show a novel proliferation process. This should be the reflection of the nature that the localized molecular orientational waves of the solitons propagate as pulses.

 This study was published in Nature Communications on 26, June 2020.

*Satoshi Aya, Fumito Araoka, Kinetics of motile solitons in nematic liquid crystals, Nature Communications, 10.1038/s41467-020-16864-8

Directional propagation (upper) and proliferation process (bottom) of the liquid crystal solitons. 

Soliton: Also called solitary wave. It is a wave packet, which can transport for a long distance