Electrohydrodynamic instabilities in freely suspended smectic C films

Electrohydrodynamic convection in freely suspended smectic films is investigated experimentally by means of reflection polarizing microscopy. A two-dimensional vortex now is observed when an electric field is applied in the plane of the smectic layers and the electrodes are in contact with the film. This type of convection has been studied in smectic A, nematic and isotropic films before. For the first time we present measurements of the vortex mode in smectic C films and ferroelectric smectic C*-films. The convective flow within the optically anisotropic smectic C layers can be visualized directly due to the optical textures resulting from the non-uniform c-director field. In ferroelectric smectic C*-films additional director reorientation effects due to the interaction between the applied electric field and tile spontaneous polarization are observed.