We present a high-resolution study of the isotropic to nematic phase transition of a low birefringence liquid-crystal compound incorporating an aerosil gel. Calorimetry, light scattering, and microscopy data coherently combine to allow for an accurate determination of the temperature dependence of the onset of the nematic state. The nematic order develops on cooling through two distinct processes while the nematic correlation length mildly decreases.We understand the doubling of the phase transition as due to a crossover from a random-dilution regime, where the silica gel couples to the scalar part of the nematic order parameter, to a low-T random-field regime, where the coupling induces distortions in the director field.

Isotropic to Nematic Transition of Aerosil-Disordered Liquid Crystals / M. Caggioni, A. Roshi, S. Barjami, F. Mantegazza, G. S. Iannacchione, T. Bellini. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 93:12(2004 Sep 17), pp. 127801-1-127801-4.

Isotropic to Nematic Transition of Aerosil-Disordered Liquid Crystals

M. Caggioni;T. Bellini
2004-09-17

Abstract

We present a high-resolution study of the isotropic to nematic phase transition of a low birefringence liquid-crystal compound incorporating an aerosil gel. Calorimetry, light scattering, and microscopy data coherently combine to allow for an accurate determination of the temperature dependence of the onset of the nematic state. The nematic order develops on cooling through two distinct processes while the nematic correlation length mildly decreases.We understand the doubling of the phase transition as due to a crossover from a random-dilution regime, where the silica gel couples to the scalar part of the nematic order parameter, to a low-T random-field regime, where the coupling induces distortions in the director field.
Settore FIS/07 - Fisica Applicata(Beni Culturali, Ambientali, Biol.e Medicin)
PHYSICAL REVIEW LETTERS
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/16915
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