A NEW TYPE OF LAYER STRUCTURE DEFECTS IN CHIRAL SMECTICS

Under a low frequency AC electric field applied to the S(A) phase an apparently homogeneous planar structure is obtained which is in fact composed of a system of parallel stripes perpendicular to the smectic layers. This texture persists even in the S(c)* phase. The stripes are explained as a contrast on elongated focal conics originating from undulations of smectic layers. Such undulations are formed as a consequence of a reduction in the smectic layer thickness due to the electroclinic effect. The deformation of smectic layers has been calculated on the basis of the elastic free energy associated with their deformation.