Two-dimensional skyrmions and other solitonic structures in confinement-frustrated chiral nematics

Paul J. Ackerman, Rahul P. Trivedi, Bohdan Senyuk, Jao van de Lagemaat, and Ivan I. Smalyukh
Phys. Rev. E 90, 012505 – Published 10 July 2014

Abstract

We explore spatially localized solitonic configurations of a director field, generated using optical realignment and laser-induced heating, in frustrated chiral nematic liquid crystals confined between substrates with perpendicular surface anchoring. We demonstrate that, in addition to recently studied torons and Hopf-fibration solitonic structures (hopfions), one can generate a host of other axially symmetric stable and metastable director field configurations where local twist is matched to the surface boundary conditions through introduction of point defects and loops of singular and nonsingular disclinations. The experimentally demonstrated structures include the so-called “baby-skyrmions” in the form of double twist cylinders oriented perpendicular to the confining substrates where their double twist field configuration is matched to the perpendicular boundary conditions by loops of twist disclinations. We also generate complex textures with arbitrarily large skyrmion numbers. A simple back-of-the-envelope theoretical analysis based on free energy considerations and the nonpolar nature of chiral nematics provides insights into the long-term stability and diversity of these inter-related solitonic field configurations, including different types of torons, cholestric-finger loops, two-dimensional skyrmions, and more complex structures comprised of torons, hopfions, and various disclination loops that are experimentally observed in a confinement-frustrated chiral nematic system.

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  • Received 4 March 2014

DOI:https://doi.org/10.1103/PhysRevE.90.012505

©2014 American Physical Society

Authors & Affiliations

Paul J. Ackerman1,2, Rahul P. Trivedi1,2, Bohdan Senyuk1, Jao van de Lagemaat3,1,5, and Ivan I. Smalyukh1,2,4,5,*

  • 1Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
  • 2Department of Electrical, Computer and Energy Engineering, University of Colorado, Boulder, Colorado 80309, USA
  • 3National Renewable Energy Laboratory, Golden, Colorado 80401, USA
  • 4Liquid Crystal Materials Research Center and Materials Science and Engineering Program, University of Colorado, Boulder, Colorado 80309, USA
  • 5Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, Colorado 80309, USA

  • *ivan.smalyukh@colorado.edu

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Vol. 90, Iss. 1 — July 2014

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