PHASE-TRANSITION AND DEFECTS IN A THIN NEMATIC FILM

We derive a set of general equations of the Landau-Ginzburg type descr ibing the spatiotemporal evolutions of the tensorial order parameter o f the nematic phase. We study numerically, for a particular case (thin nematic film), the equilibrium points and the dynamical behavior (pat tern formation, nucleation and growth processes, and defects) of the i sotropic-anisotropic phase transition. We discuss the biaxial zones, w hich are located at the core of the defects and at the interfaces of t he nucleating domains, and the shape of these nuclei.