研究目的
To demonstrate how the geometric shape of a rod in a nematic liquid crystal can stabilise a large number of oppositely charged topological defects and to support the Gauss–Bonnet theorem.
研究成果
The work demonstrates that complex topology can be realized on simple objects with genus g = 0 by geometric shaping of rods/cylinders, which acts as a stabilizing factor preventing defect annihilation. This shaping introduces energy barriers between neighboring and oppositely charged topological defects, preventing their movement and subsequent annihilation. The results support the Gauss–Bonnet theorem, indicating that the total topological charge of all hedgehog defects on an object should be equal to g (cid:2) 1, where g is the genus of the particle.
研究不足
The study is limited by the complexity of the topological states that can be realized on simple objects and the precision required in fabricating and manipulating the micro-structures. The exact values of the energy barriers and the smallest separation at which defects are still stable require further numerical modeling.
1：Experimental Design and Method Selection:
The study involves the creation and manipulation of topological defects on helical colloids and grooved rods in nematic liquid crystals using laser tweezers. The methodology includes the use of direct laser writing for fabricating micro-helices and micro-grooved cylinders, and the application of laser tweezers for defect manipulation.
2：Sample Selection and Data Sources:
Micro-helices and micro-grooved cylinders were fabricated using a direct laser writing system. The samples were treated for homeotropic anchoring of the surrounding nematic liquid crystal (5CB).
3：List of Experimental Equipment and Materials:
Direct laser writing system (Photonic Professional, Nanoscribe GmbH), UV-sensitive polymer photoresist (IP-L 780), nematic liquid crystal (5CB), DMOAP silane for surface treatment, laser tweezers setup built around an inverted microscope (Nikon Eclipse, TE2000-U).
4：Experimental Procedures and Operational Workflow:
The micro-structures were fabricated, treated for homeotropic anchoring, and then dispersed in the nematic liquid crystal. Topological defects were created and manipulated using laser tweezers. The interaction between defects and the geometric stabilisation were observed and analyzed.
5：Data Analysis Methods:
The analysis involved observing the behavior of topological defects under different conditions, using optical microscopy and laser tweezers for manipulation and observation.
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