Holes and disclinations in hybrid nematic liquid crystal films.

Defect patterns in hybrid nematic liquid crystal films of pentylcyanobiphenyl (5CB) on a glycerol surface were studied with polarized transmission and monochromatic reflected light microscopy. We report that disclinations of apparent topological strength zero, stable pairs of +1 and -1 disclinations, and higher strength defects found in these films are stabilized by holes in the liquid crystal film. These holes are produced by a monolayer of surfactant on the glycerol surface. In addition, we describe the topology of the director field in the film during the coalescing of two such holes.