Featured Liquid Crystal Picture Art of the Month

July 2024

©Kamal Thapa

Splitting dislocations

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Description

Defects such as dislocations are ubiquitous in condensed matter physics. The picture represents the splitting of a thick edge dislocation with Burgers vector full pitch into two thin edge dislocations with Burgers vector half pitch on heating the sample from antiferroelectric chiral smectic to paraelectric cholesteric phase. The photo is taken using a polarizing optical microscope (Nikon OPTIPHOT2- POL equipped with an objective: M Plan , N.A. 0.14, Nikon Instruments Inc.) under crossed polarizers in an antiparallel buffed wedge cell at cholesteric phase, 100 C. The wedge cell is filled with a chiral mixture DIO:R1011 = 99.8:0.2 (wt.%), where DIO is a ferroelectric nematic material and R1011 is a chiral additive.

A detailed study on how the orientational order of three different chiral liquid crystal phases, a paraelectric cholesteric, an antiferroelectric chiral smectic, and a ferroelectric cholesteric, affect the structure of edge dislocations is published in
https://journals.aps.org/pre/abstract/10.1103/PhysRevE.109.054702.

Author

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Kamal Thapa is a Ph.D. student, currently working with Dr. Oleg D. Lavrentovich at the Advanced Materials and Liquid Crytal Institute (AMLCI), Kent State University, Kent, Ohio. His research focuses on topological defects and electro-optics of chiral and ferroelectric nematic liquid crystals. Kamal is a recipient of the 2023 AMLCI Alfred Saupe Fellowship for an outstanding graduate student working on the physics or material sciences of liquid crystals.

Contact email: kthapa(at)kent.edu

ResearchGate: https://www.researchgate.net/profile/Kamal-Thapa-11

LinkedIn: https://www.linkedin.com/in/kamal-thapa-22bb69235/

Research group website: https://lavrentovichgroup.com/

Jury comment

The equilibrated combination of vibrant colors and dislocations occurring at the phase transition aesthetically portrays the beauty of the science of liquid crystals.
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