The production of strings (disclination lines and loops) has been observed by means of the Kibble mechanism of domain (bubble) formation in the isotropic-nematic phase transition of the uniaxial nematic liquid crystal 4-cyano-4'-n-pentylbiphenyl. The number of strings formed per bubble is about 0.6. This value is in reasonable agreement with a numerical simulation of the experiment in which the Kibble mechanism is used for the order parameter space of a uniaxial nematic liquid crystal.

The Cosmological Kibble Mechanism in the Laboratory: String Formation in Liquid Crystals

We study influence of a weak disorder on 1st and 2nd order phase transitions in which a continuous symmetry is broken. As illustrative cases we choose the isotropic-nematic (I-N) and nematic-smectic A (N-SmA) liquid crystal phase transitions. We yield an explanation for the established domain pattern and estimate the phase behaviour as a function of the disorder strength.

Said Besˇlagič

Papers

Phase Behaviour and Structure of Weakly Perturbed Liquid Crystals