title: Glassy dynamics in the isotropic phase of a smectogenic liquid crystalline compound.
abstract: The temperature evolution of the primary relaxation time in the isotropic phase of 4-cyano-4'-tetradecylbiphenyl (14CB) above the isotropic-smectic A (I-SmA) transition is discussed. Based on the enthalpy space and distortion-sensitive analysis, the prevalence of the mode coupling theory (MCT) "critical" and "glassy" dynamics is shown. The obtained singular dependence is related to the MCT critical temperature located approximately 48 K below the clearing (I-SmA) temperature. However, a weak but detectable distortion in the immediate vicinity of the transition occurs. It is also shown that the value of the fragile strength coefficient D(T) is characteristic of a very fragile glassy liquid whereas the steepness index m is typical of a strong one. Both magnitudes anomalously change on approaching the I-SmA phase transition. The static permittivity shows the pretransitional effect linked to the temperature of the hypothetical continuous phase transition located approximately 10.2 K below the I-SmA transition.
authors: Institute of High Pressure Physics, Polish Academy of Sciences, ulica Sokołowska 27/39, PL-00-143 Warsaw, Poland. sylwester.rzoska@gmail.com
authors: Sylwester J
authors: SJ
authors: Rzoska
authors: Sebastian
authors: S
authors: Pawlus
authors: Krzysztof
authors: K
authors: Czupryński