Siloxane antiferroelectric liquid crystalline dimer exhibiting two field-free zero birefringent states

We studied the optical and electro-optical properties of a siloxane antiferroelectric liquid crystalline dimer exhibiting a large molecular tilt that reached a maximum value of 53°. When the molecular tilt angle in the antiferroelectric phase exceeded 45°, it was found that the field-free position of the slow vibration direction, which corresponds to the largest refractive index, flipped from a position along the smectic layer normal, to a position perpendicular to it. When the tilt angle became 45°, a zero birefringent state, which was theoretically predicted by de Meyere in 1996, was also found to occur twice in the antiferroelectric phase of the siloxane dimer.