1,095,749 research outputs found
The Surface Electroclinic Effect near the First Order Smectic-A*--Smectic-C* transition
We analyze the surface electroclinic effect (SECE) in a material that
exhibits a first order bulk smectic- (Sm-) -- smectic-
(Sm-) transition. The effect of a continuously varying degree of
enantiomeric excess on the SECE is also investigated. We show that due to the
first order nature of the bulk Sm- -- Sm- transition, the SECE can be
unusually strong and that as enantiomeric excess is varied, a jump in surface
induced tilt is expected. A theoretical state map, in enantiomeric excess -
temperature space, features a critical point which terminates a line of first
order discontinuities in the surface induced tilt. This critical point is
analogous to that found for the phase diagram (in electric field - temperature
space) for the bulk electroclinic effect. Analysis of the decay of the surface
induced tilt, as one moves from surface into bulk shows that for sufficiently
high surface tilt the decay will exhibit a well defined spatial kink within
which it becomes especially rapid. We also propose that the SECE is
additionally enhanced by the de Vries nature (i.e. small layer shrinkage at the
bulk Sm-A* -- Sm-C* transition) of the material. As such the SECE provides a
new means to characterize the de Vries nature of a material. We discuss the
implications for using these materials in device applications and propose ways
to investigate the predicted features experimentally
- β¦