CONVECTIVE INSTABILITIES IN HOMEOTROPIC NEMATICS: PATTERNS AND DYNAMICAL EFFECTS IN NONLINEAR REGIMES

Abstract

We present experimental results showing the convective patterns near to and far from the threshold in a horizontal film of Homeotropic Nematics subjected to an inverse vertical thermal gradient. Depending on the intensity of the applied external magnetic fields, two transitions are studied: square–hexagons and hexagon–square. In all cases, there is a coexistence of two kinds of pattern. The temporal evolution of structures was also observed, and so, mechanisms including this dynamic are proposed for the transitions between patterns.