6533b7dbfe1ef96bd126f814

RESEARCH PRODUCT

Textures in hexatic films of nonchiral liquid crystals: Symmetry breaking and modulated phases

subject

description

Novel modulated textures, such as stripes and multiarmed star defects, have been observed in freely suspended films of nonchiral liquid crystals just below the smectic-$C$ to hexatic phase transition. Detailed studies using depolarized reflection microscopy suggest that the stripes are locally chiral surface splay domains of the smectic-$L$ phase, a tilted hexatic not previously identified in thermotropic liquid crystals. Line defects which form additional domain walls in the hexatic lattice lead to characteristic modulations of the basic one-dimensional stripe pattern. Inside thick circular islands, for example, stripes form circumferentially and the lines form centered 12-armed stars, resulting in a regular arrangement of hexatic domains in the form of a brick wall pattern. The observation that line defects which are not pinned at the film boundaries always form closed loops supports a model of the stripe pattern based on local chiral symmetry breaking.