GROWTH INSTABILITY AND PRICKING-FRACTURE MECHANISM IN SMECTIC-A FOCAL-CONIC NUCLEATION

We show that smectic- A plates growing from the top of isotropic dropl ets are subject to an interfacial growth instability. This instability occurs before the static textural instability already known which pro duces focal conics in order to relax the smectic- A -isotropic surface energy. We study the growth instability and its relation with the tun neling through the barrier of the first-order static instability. We f ind that the focal conics nucleate on the nonlinearities of the growth instability through a fracture mechanism.