Stability of the director profile of a nematic liquid crystal around a spherical particle under an external field

J. Fukuda, H. Yokoyama

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

We study numerically the effect of an external magnetic or electric field on the director profiles of a nematic liquid crystal around a spherical particle. We pay particular attention to the stability of a hyperbolic hedgehog defect accompanying the particle, which transforms into a Saturn-ring defect encircling the particle under a sufficiently strong external field. We focus on the particle size dependence of the two important threshold field strengths: the "thermodynamic-transition" field strength H 1 at which the hedgehog and the Saturn-ring configurations have the equal free energy, and the critical field strength H 2 at which the hedgehog loses its (meta)stability. Our numerical results demonstrate that while H 1 is non-monotonically dependent on the particle radius R 0, H 2 monotonically increases with R 0 and the dependence of H 2 is weak for large R 0. The non-monotonic dependence of H 1 on R 0 can be explained by comparing the energies of the two configurations and assuming the dependence of those energies on a rescaled field. A crude argument of the energetics of a hyperbolic hedgehog defect under an external field shows that for an asymptotically large R 0 the critical field strength is independent of R 0, which agrees with our numerical finding.

Original languageEnglish
Pages (from-to)341-347
Number of pages7
JournalEuropean Physical Journal E
Volume21
Issue number4
DOIs
Publication statusPublished - Dec 1 2006
Externally publishedYes

Fingerprint

Saturn
Liquid Crystals
Nematic liquid crystals
liquid crystals
field strength
Defects
Saturn rings
profiles
Thermodynamics
Particle Size
defects
Free energy
Particle size
Electric fields
Magnetic fields
configurations
metastable state
free energy
thermodynamics
radii

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Biophysics
  • Chemistry(all)
  • Materials Science(all)
  • Surfaces and Interfaces

Cite this

Stability of the director profile of a nematic liquid crystal around a spherical particle under an external field. / Fukuda, J.; Yokoyama, H.

In: European Physical Journal E, Vol. 21, No. 4, 01.12.2006, p. 341-347.

Research output: Contribution to journalArticle

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