Self-organization of N* inclusions in SmC* free-standing films

The behaviour of freely suspended smectic-C* (SmC*) films at the bulk SmC*-cholesteric (N*) phase transition has been investigated using polarized-reflected-light microscopy. Our experimental observations show that above the bulk SmC*-N* phase transition the N* order appears in different ways according to the film thickness. In thin films, the conventional layer-by-layer thinning occurs. In films of intermediate thickness N* inclusions nucleate inside the SmC* film. The distortions of the in-plane orientational order of the SmC* host phase induce elastic interactions between the inclusions and lead to their self-organization in chain-like structures. Both the dynamic of the chaining and the parameters driving the equilibrium distance between the inclusions in the chain are investigated. In thick films, N* fingers grow inside the film. The influence of the experimental conditions on the various processes is analysed.