Electric field-induced nucleation and growth of focal-conic and stripe domains in a smectic A liquid crystal |
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Authors: | Shila Garg Corresponding author Kirstin Purdy Erica Bramley I I Smalyukh O D Lavrentovich |
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Institution: | 1. Department of Physics , The College of Wooster , Wooster, OH 44691, USA;2. Chemical Physics Interdisciplinary Program and Liquid Crystal Institute , Kent State University , Kent, OH 44242, USA |
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Abstract: | We have studied the electric field-induced first order transition from a homeotropic smectic A structure to a polydomain texture that occurs through the nucleation of toric focal-conic domains (TFCDs). The process involves two steps: first, nucleation of TFCDs of a size larger than a critical radius a*, and then a steady growth of TFCDs to a secondary critical radius a**, when surface anchoring effects become dominant and cause a transition from a circular TFCD to an elongated stripe domain (SD). Studies were performed for pure smectic A materials and for smectic A doped with kunipia nanoparticles. Non-destructive 3D imaging with fluorescence confocal polarizing microscopy showed that field-induced TFCDs can nucleate in the smectic A bulk. Clay particles reduce the energy barrier for nucleation as they distort the smectic A layers and thus increase the ground state energy. Simple elastic models of the TFCD and SD allow us to describe the qualitative features of the observed phenomena. |
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