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

• Authors: Ioannis Lelidis , Giovanni Barbero , Antonio Scarfone
• Languages of publication: EN

Abstracts

EN

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.

Keywords

EN

continuum models and theories of liquid crystal structure; cholesteric-nematic transition

• Publisher: De Gruyter Open
• Journal: Open Physics
• Year: 2012
• Volume: 10
• Issue: 3
• Pages: 587-593

Dates

published

1 - 6 - 2012

online

17 - 6 - 2012

Contributors

author

Ioannis Lelidis

author

Giovanni Barbero

• Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Torino, Italia

author

Antonio Scarfone

• 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

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Identifiers

DOI

10.2478/s11534-012-0050-y