Abstract
Phase transitions and critical phenomena have been central subjects in condensed-matter physics, where calorimetric investigations play a significant role. In this review, we focus on the study of critical heat anomaly in liquid crystalline phase transitions. Liquid crystals exhibit amazingly wide variety of phases, and therefore provide attractive examples for studying the phase transitons and critical phenomena. First, some of the basic liquid crystalline phases are described, and then elementary ideas of critical phenomena and universality are briefly reviewed. Developments in high-precision calorimetric techniques have greatly contributed to the investigations of critical phenomena in liquid crystal systems. In this review, analyses of critical heat anomalies have been described in detail: necessity of including critical constant term, correction terms, and also data-range shrinking, etc. Finally, examples of recent investigations are shown. The critical heat anomaly observed in antiferroelectric liquid crystals exhibits crossover from 3D XY to tricritical behavior. The results on the de Vries Sm-A-Sm-C phase transition are also displayed.
