抄録
In the antiferroelectric smectic liquid crystals the V-shaped response of the transmittance of light to the electric field is observed, where the transition between antiferroelectric and ferroelectric phases looks as if there is no threshold between both phases and even the structure of the antiferroelectric phase is now controversial. On the other hand the antiferromagnetic Ising model with layered structure is known to have a tricritical point in the magnetic field, in which the transition between antiferromagnetic and ferromagnetic phases induced by the magnetic field can be continuous. From this point the phenonnena observed in the antiferroelectric smectics is to be explained in terms of the antiferromagnetic Isimg model with layered structure.
