Nontraditional phase transitions in liquid crystals
L.D. Landau Institute for Theoretical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region, Russian Federation
According to classical textbooks on thermodynamics or statistical physics, there are only two types of phase transitions—continuous, or second-order phase transitions in which the latent heat L is zero, and the first-order phase transitions in which L ≠ 0. Present day textbooks and monographs also mention yet another, stand-alone type—the Berezinskii—Kosterlitz—Thouless transition, which is relevant only in two dimensions and which shares some features with the former two. This paper discusses examples of nontraditional thermodynamic behavior (i.e., which is inconsistent with the theoretical phase transition paradigm now universally accepted). For phase transitions in smectic liquid crystals, mechanisms for nonconventional behavior are proposed and predictions they imply are examined.