抄録
Phase transition of a freely suspended chiral smectic film exhibiting the first order phase transition at a bulk system is studied in the framework of a phenomenological theory, in which such a widely observed fact is taken into account that the surface layer orders at a temperature higher than the bulk critical temperature. In case the system is thinner than a critical thickness, a continuous change occurs in agreement with the experimental fact. A mechanism of the continuous change is elucidated on the basis of the phase diagram of the bulk system on the field versus temperature plane, where non-uniformity due to the ordered surface layers is replaced by an effective field and a high temperature phase is connected continuously to a low temperature one by insertion of an unstable state between them.
