Cascade of structures in the thermoconvection of a nematic in the director-dominated regime

We report on the first experimental study of the nonlinear evolution of thermoconvection in a planar nematic liquid crystal, in extended geometry and at zero or weak stabilizing magnetic field. As the control parameter is adiabatically increased, we show that the system undergoes a series of bifurcations between stationary convective structures. We stress that this scenario is generic in the convection of a nematic in a regime where the director nonlinear couplings dominate, independently of the basic convective mechanism