Tunable three-dimensional architecture of nematic disclination lines

Area of Science:

• Physics
• Materials Science
• Soft Matter Physics

Background:

• Disclination lines are critical topological defects in materials, influencing phenomena from material fracture to cosmic structure formation.
• Controlling disclinations is essential for advancing technologies like electro-optics, programmable materials, and active matter systems.

Purpose of the Study:

• To introduce a theoretical framework for experimentally tailoring three-dimensional (3D) disclination architecture in nematic liquid crystals.
• To provide quantitative predictions for disclination line connectivity and shape in confined nematics.
• To establish methods for practical control and understanding of these defect lines.

Main Methods:

• Developed a theoretical model for nematic liquid crystals confined between patterned substrates, drawing analogies to magnetostatics.
• Utilized polarized light to pattern the in-plane alignment of liquid crystal molecules.
• Conducted experimental tests and computer simulations to verify predictions and identify tuning parameters.

Main Results:

• Disclination lines were predicted to connect defects of the same topological charge on opposing surfaces.
• Disclination lines were found to be attracted to regions of maximum twist within the liquid crystal.
• Experimental results and simulations matched across different length scales using identified nondimensional parameters.

Conclusions:

• The study presents a robust theoretical and experimental framework for controlling 3D disclination lines in nematic liquid crystals.
• This work offers a practical method for understanding and manipulating defect lines, paving the way for novel applications.
• The findings are crucial for the design of advanced materials and devices leveraging topological defects.