Decomposition of strongly charged topological defects

Area of Science:

• Soft Matter Physics
• Topological Defects
• Nematic Systems

Background:

• Nematic topological defects are crucial in condensed matter physics.
• Understanding their behavior, especially decomposition, is key to controlling material properties.
• Large defect strengths present unique theoretical and experimental challenges.

Purpose of the Study:

• To theoretically analyze the decomposition of large nematic topological defects.
• To identify and characterize the mechanisms and scenarios governing defect decomposition.
• To experimentally validate theoretical predictions for defect behavior.

Main Methods:

• Mesoscopic Landau-de Gennes theory using the tensor nematic order parameter.
• Analysis of defect core structures.
• Experimental enforcement of topological defects using atomic force microscopy (AFM) scribing.
• Observation of defect arrays in a plane-parallel nematic cell.

Main Results:

• Demonstrated a robust tendency for large nematic defects to decompose into elementary units.
• Identified two distinct theoretical scenarios for defect decomposition based on imposed total defect strengths.
• Successfully enforced and observed arrays of defects with strengths m=±1 and m=±2.
• Experimental results align with theoretical predictions.

Conclusions:

• The decomposition of large nematic topological defects is a predictable phenomenon.
• The Landau-de Gennes approach effectively describes defect core behavior and decomposition.
• AFM scribing provides a viable method for creating and studying topological defects experimentally.