RESUMEN
Despite their simple structure, spatially homogeneous modes can participate directly in pattern-formation processes. This is demonstrated by new experimental and theoretical results for thermo- and electroconvection in planar nematic liquid crystals, where two distinct homogeneous modes, twist and splay distortions of the director field, emerge. Their nonlinear excitation is due to certain spontaneous symmetry-breaking bifurcations.
RESUMEN
The evolution of the isolated domains of a bifurcated structure in a subcritical state is experimentally studied along the hysteresis branch, up to the critical point at which a chaotic regime is found to develop. The width of the domains is unstable and the fronts dynamics exhibit a cascade of bifurcations as the constraint increases. The chaotic regime is initiated by a splitting of the isolated domains, controlled by a width-selection mechanism. Most of these results are qualitatively reproduced in a fifth-order Ginzburg-Landau model.