Annihilation of highly-charged topological defects

Eva Klemenčič (Author), Pavlo Kurioz (Author), Milan Ambrožič (Author), Charles Rosenblatt (Author), Samo Kralj (Author)

Abstract

We studied numerically external stimuli enforced annihilation of a pair of daughter nematic topological defect (TD) assemblies bearing a relatively strong topological charge |m|=3/2. A Landau- de Gennes phenomenological approach in terms of tensor nematic order parameter was used in an effectively two-dimensional Cartesian coordinate system, where spatial variations along the z-axis were neglected. A pair of {m=3/2,m=−3/2} was enforced by an appropriate surface anchoring field, mimicking an experimental sample realization using the atomic force microscope (AFM) scribing method. Furthermore, defects were confined within a rectangular boundary that imposes strong tangential anchoring. This setup enabled complex and counter-intuitive annihilation processes on varying relevant parameters. We present two qualitatively different annihilation paths, where we either gradually reduced the relative surface anchoring field importance or increased an external in-plane spatially homogeneous electric field E. The creation and depinning of additional defect pairs {12,−12} mediated the annihilation in such a geometry. Furthermore, we illustrate the absorption of TDs by sharp edges of the confining boundary, accompanied by m=±1/4↔∓1/4 winding reversal of edge singularities, and also E-driven zero-dimensional to one-dimensional defect core transformation.

Keywords

liquid crystals;topological defects;annihilation;order reconstruction;

Data

Language:	English
Year of publishing:	2020
Typology:	1.01 - Original Scientific Article
Organization:	UM FNM - Faculty of Natural Sciences and Mathematics
Publisher:	MDPI
UDC:	532.783
COBISS:	27325443
ISSN:	2073-4352
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Downloads:	0
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Other data

Secondary language:	Slovenian
Secondary keywords:	tekoči kristali;topološki defekti;anihilacija;rekonstrukcija reda;
Type (COBISS):	Scientific work
Pages:	str. 1-13
Volume:	ǂVol. ǂ10
Issue:	ǂno. ǂ8
Chronology:	Aug. 2020
DOI:	10.3390/cryst10080673
ID:	25769847