Publication:
Capillary and winding transitions in a confined cholesteric liquid crystal

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dc.affiliation.dptoUC3M. Departamento de Matemáticases
dc.affiliation.grupoinvUC3M. Grupo de Investigación: Interdisciplinar de Sistemas Complejos (GISC)es
dc.contributor.authorDe Las Heras, Daniel
dc.contributor.authorVelasco, Enrique
dc.contributor.authorMartínez-Ratón, Yuri
dc.contributor.funderMinisterio de Economía y Competitividad (España)es
dc.date.accessioned2020-07-15T12:11:33Z
dc.date.available2020-07-15T12:11:33Z
dc.date.issued2015-01-01
dc.description.abstractWe consider a Lebwohl-Lasher model of chiral particles confined in a planar cell (slit pore) under different boundary conditions, and solve it using mean-field theory. The phase behaviour of the system with respect to temperature and pore width is studied. Two phenomena are observed: (i) an isotropic-cholesteric transition, which exhibits an oscillatory structure with respect to pore width, and (ii) an infinite set of winding transitions caused by commensuration effects between cholesteric pitch and pore width. The latter transitions have been predicted and analysed by other authors for cholesterics confined in a fixed pore and subjected to an external field promoting the uniaxial nematic phase; here we induce winding transitions solely from geometry by changing the pore width at zero external field (a setup recently explored in atomic-force microscopy experiments). In contrast with previous studies, we obtain the phase diagram in the temperature vs. pore width plane, including the isotropic-cholesteric transition, the winding transitions and their complex relationship. In particular, the structure of winding transitions terminates at the capillary isotropic-cholesteric transition via triple points where the confined isotropic phase coexists with two cholesterics with different helix indices. For symmetric and asymmetric monostable plate anchorings the phase diagrams are qualitatively similar.en
dc.description.abstractWe consider a Lebwohl–Lasher model of chiral particles confined in a planar cell (slit pore) under different boundary conditions, and solve it using mean-field theory. The phase behaviour of the system with respect to temperature and pore width is studied. Two phenomena are observed: (i) an isotropic–cholesteric transition, which exhibits an oscillatory structure with respect to pore width, and (ii) an infinite set of winding transitions caused by commensuration effects between cholesteric pitch and pore width. The latter transitions have been predicted and analysed by other authors for cholesterics confined in a fixed pore and subjected to an external field promoting the uniaxial nematic phase; here we induce winding transitions solely from geometry by changing the pore width at zero external field (a setup recently explored in atomic-force microscopy experiments). In contrast with previous studies, we obtain the phase diagram in the temperature vs. pore width plane, including the isotropic–cholesteric transition, the winding transitions and their complex relationship. In particular, the structure of winding transitions.terminates at the capillary isotropic–cholesteric transition via triple points where the confined isotropic phase coexists with two cholesterics with different helix indices. For symmetric and asymmetric monostable plate anchorings the phase diagrams are qualitatively similar.en
dc.description.sponsorshipThis work was partially financed by the Portuguese Foundation for Science and Technology (FCT) through grant PTDC/FIS/ 119162/2010. E.V. also acknowledges support from MINECO (Spain) through grant FIS2013-47350-C5-1-R.en
dc.identifier.bibliographicCitationSoft Matter, 11 (35), 2015, pp. 7038-7045
dc.identifier.doihttps://doi.org/10.1039/c5sm01036e
dc.identifier.issn1744-683X
dc.identifier.publicationfirstpage7038
dc.identifier.publicationissue35
dc.identifier.publicationlastpage7045
dc.identifier.publicationtitleSoft Matter
dc.identifier.publicationvolume11
dc.identifier.urihttps://hdl.handle.net/10016/30704
dc.identifier.uxxiAR/0000017241
dc.language.isoeng
dc.publisherRoyal Society of Chemistry
dc.relation.projectIDGobierno de España. FIS2013-47350-C5-1-R.
dc.rights©The Royal Society of Chemistry 2015
dc.rights.accessRightsrestricted access
dc.subject.ecienciaMatemáticases
dc.titleCapillary and winding transitions in a confined cholesteric liquid crystalen
dc.typeresearch article*
dc.type.hasVersionVoR*
dspace.entity.typePublication
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