Photopyroelectric high resolution ac calorimetry has been used to study the nematic-isotropic phase transition in octylcyanobiphenyl liquid crystal incorporating an aerosil soft gel. We have found that the sample is not in thermodynamic equilibrium in the two phase coexistence region, as shown by the frequency dependence of the double peak in the specific heat and by its thermal hysteresis. The results suggest that the dynamics of the system becomes slower as it is cooled over the transition temperature. An explanation for the formation of a nematic glassy phase in liquid crystals with quenched disorder based on the similarity of these results with the ones obtained in other disordered materials is attempted.

• Received 26 February 2005

DOI:https://doi.org/10.1103/PhysRevLett.94.247801