Topologically non-equivalent textures generated by the nematic electrohydrodynamics

ABSTRACT

Some classes of nematic liquid crystals can be driven through turbulent regimes when forced by an external electric field. In contrast to isotropic fluids, a turbulent nematic exhibits a transition to a stochastic regime that is characterised by a network of topological defects. We study the deformations arising after the electric field has been switched-off. In contrast to the turbulent regime, the relaxation of this topological-defect regime involves the annihilation of an interlacement of defect lines. We show that these defect lines separate regions of the nematic having topologically non-equivalent textures.

Graphical Abstract

KEYWORDS:

• Nematic liquid crystals
• twist deformation
• topological defects
• electrohydrodynamics

Acknowledgments

We thank Alfredo Pane for having prepared the experimental cells, and acknowledge Jonasz Słomka and Ridha Hamdi for useful discussions.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data can be accessed here.

Notes

1. We note here that at the threshold $V_0\simeq V_c$ the relaxation time is usually defined as ${\tau }_D={\gamma }_1{d}^2/k_{11}$ [4], because the static distortion has periodicity $\sim d$. For $V_0>V_c$ the distortion periodicity is reduced to $D<d$.

Additional information

Funding

This work was supported by Ministero dell’Istruzione, dell’Università e della Ricerca [PRIN 2010LKE4CC_008].