Orientational action of edge dislocations on the director field in antiferroelectric smectic-C_A∗ films

摘要

We report imaging of the director field near edge dislocations in thermotropic antiferroelecric smectic-C_A∗(SmC_A∗) liquid crystal. Measurements were made in freestanding films with thickness from two to ten smecticlayers. We find two different orientations of the molecular tilt plane with respect to the edge dislocation line.The orientation is determined by the value of the Burgers vector of the dislocation. Elementary edge dislocationand dislocations with a Burgers vector equal to an odd number of layers orient the tilt plane perpendicular onthe two sides of the dislocation. Dislocations with a Burgers vector equal to an even number of layers orient themolecular tilt plane parallel to the dislocation line. Difference in the orientation for an odd Burgers vector can beattributed to breaking of antiferroelectric symmetry by the edge dislocation.