Nature of disclination cores in liquid crystals

A disclination is an orientation symmetry-breaking defect and its strength corresponds to the number of rotations (in multiples of 2π) of the director over a path encircling the disclination. The line core plays a considerable role in the disclination energy balance and mobility, however, the detailed nature of the core structure is largely unknown. Here we demonstrate different core structures for different disclinations by using transmission electron microscopy and atomic force microscopy coupled with the nanostripe decoration technique. We show that the molecular distribution in the core of (+1) defects changes from the prolate planar to oblate homeotropic, resembling but not identical to 'escape into the third dimension'. The homeotropic (-1) defect appears to possess an isotropic core, contrary to theoretical predictions.