Subphases in antiferroelectric liquid crystalline binary mixtures with infinite helical pitch or zero spontaneous polarization

Abstract

Abstract In binary mixtures with zero spontaneous polarization, SmCα* exists in every mixing ratio, while the other subphases, SmCA(qT), disappear rather abruptly with mixing. On the contrary, both of the subphases are observed in binary mixtures with considerably long helical pitch length. These observations suggest that it is the spontaneous polarization but not the helicoidal structure that plays an important role for the appearance of SmCA*(qT). The long range repulsive interactions necessary for describing SmCA*(qT) as a Devil's staircase by the one-dimensional Ising model must originate from the collective polarization fluctuations as proposed recently by Prost and Bruinsma. The remaining subphase, SmCA*, is supposed to be a smectic C like phase where the intra-and inter- layer correlations of molecular tilting are very much reduced and to be caused by high smectic layer order and weak pair forming ability.