NEMATIC ELECTROCLINIC EFFECT

A tilt of the principal axis of the optical dielectric tensor linear in a transverse electric field was observed for a surface-stabilized nematic liquid crystal. The electroclinic coefficient d/dE was observed to increase rapidly on approaching the nematicsmectic-A phase transition from above. This was not expected, and indicates that the incipient translational order is important to the electroclinic effect. The data are consistent with a critical exponent only over a narrow range of temperature, and in this range the apparent exponent is not that expected from theory. In addition, dielectric data are presented for this transition, and birefringence results are discussed. A simple theoretical discussion involving coupled order parameters is presented, and the experimental results are discussed in light of this model. © 1990 The American Physical Society.