Giant surface electroclinic effect in a chiral smectic A liquid crystal

We report the observation of a very large surface electroclinic effect in t he smectic AY phase of a chiral liquid crystal. In planar-aligned cells of enantiomerically pure W415, the smectic A* phase grows in from the isotropi c state with the layer normal rotated psi = -24 degrees from the rubbing di rection, a consequence of the surface electroclinic tilt theta (s) of the d irector. The sign of theta (s) depends on the molecular handedness, with th eta (s)=0 in the racemate, and increasing linearly with moderate enantiomer ic excess before saturating as ee --> 1. A uniform layer structure can be a chieved using cross-rubbed alignment layers, in which case thin cells of W4 15 in the smectic C* phase display V-shaped (analogue) electro-optic switch ing.