Source Title:
Open Physics
|
Volume/Issue:
Volume 10: Issue 3

Cholesteric pitch-transitions induced by a magnetic field in a sample containing incomplete number of pitches

Ioannis Lelidis, Giovanni Barbero 2 , and Antonio Scarfone 3
  • 1 Solid State Section, Department of Physics, University of Athens, Panepistimiopolis, Zografos, Athens, 157 84, Greece
  • 2 Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Torino, Italia
  • 3 ISC-CNR, Istituto dei Sistemi Complessi — Consiglio Nazionale delle Ricerche, c/o Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Torino, Italia
DOI:
https://doi.org/10.2478/s11534-012-0050-y
|
Published online:
17 Jun 2012
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Abstract

We investigate the pitch transitions induced by an external bulk field in a Cholesteric Liquid Crystal slab of finite thickness ℓ that contains an incomplete number of π-twists. The analysis is performed for a magnetic field that is (i) perpendicular to the helical axis, and (ii) tilted with respect to one of the easy directions imposed by planar and rigid boundary conditions. For finite ℓ we obtain a cascade of transitions, where the bulk expels a half-pitch at a time with increasing field to avoid divergences in the elastic energy. The dependence of the threshold magnetic field inducing the expulsion on the easy axes twist angle δ is investigated for all the cascade of pitch transitions and in particular for the final one, corresponding to the Cholesteric-Nematic transition. In the ℓ → ∞ limit this dependence disappears and we reobtain the results of de Gennes for an infinite sample.

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Journal + Issues

Open Physics

Online ISSN:
2391-5471
First published:
14 Jan 2015
Language:
English
Publisher:
De Gruyter

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