Fluctuation forces stabilizing two kinds of staircases in chiral tilted fluid smectics frustrated between ferro- and antiferro-electricity

Conventional dispersion and steric interactions between mesogenic molecules generally promote SmC*, while the interlayer orientational correlation between transverse molecular dipoles stabilizes anticlinic SmC A *. Ferroelectric and antiferroelectric orders thus produced are frustrated because of the X-Y freedom and the low-energy barrier between them. We can naturally explain not only a series of subphases between SmC A * and SmC* but also the staircase character of SmC f * emerging just below SmA by using the Casimir type long-range interaction due to polarization fluctuations, if we take account of the discrete flexoelectric polarization appropriately in addition to the ordinary one.