We study the structure of very thin liquid crystal films frustrated by antagonistic anchorings in the smectic phase. In a cylindrical geometry, the structure is dominated by the defects for film thicknesses smaller than 150 nm and the detailed topology of the defects cores can be revealed by x-ray diffraction. They appear to be split in half tube-shaped Rotating Grain Boundaries (RGB). We determine the RGB spatial extension and evaluate its energy per unit line. Both are significantly larger than the ones usually proposed in the literature
@article{arxiv.cond-mat/0510702,
title = {Structure of smectic defect cores: an X-ray study of 8CB liquid crystal ultra-thin films},
author = {Jean-Philippe Michel and Emmanuelle Lacaze and Michel Goldmann and Marc Gailhanou and Marc De Boissieu and Michel Alba},
journal= {arXiv preprint arXiv:cond-mat/0510702},
year = {2009}
}