Experimental indication of macroscopic polarization parallel to the tilt plane in free-standing films of ferroelectric liquid crystals 8SI*and DOBAMBC

Optical reflectivity and x-ray studies have been conducted on free-standing films and bulk samples of ferroelectric liquid crystals near the smectic-A -smectic-C* transition. A tilt plane rotation with respect to the direction of an applied electric field is found in the ferroelectric films above the bulk transition temperature. Whereas the macroscopic polarization is perpe ndicular to the tilt plane at low temperature, it is parallel to the tilt p lane at elevated temperature. The temperature dependence of the average til t angle is measured. (C) 1999 American Institute of Physics. [S1063-7761(99 )01410-9].