In-layer defects in smectic C materials

We investigate the director structure close to the core region of in-layer defects found in smectic C thin films. These defects are similar to nematic disclination lines in appearance and we use the Landau-de Gennes formulation for the free energy of the system previously used to consider nematic defects. The minimum energy core structures are numerically calculated and two possible structures found, where either a standard smectic A or a de Vries smectic state is formed at the centre of the defect. These two states correspond to the escaped and planar configurations of nematic disclination cores. Finally, the energies of these core structures are found as functions of the dimensions of the thin film.