Pattern Formation and Instabilities in Liquid Crystals

There are two main reasons to investigate dynamical instabilities and phase transitions in Liquid Crystals. First, the underlying physics close to phase transitions is universal and therefore applicable to other different systems. Liquid crystals are fairly easy to handle and therefore their investigation have traditionally helped for a better understanding more complex systems. Second, liquid crystals under electric fields are widely used in applications like LCD screens and mobile displays. Maybe you are just reading this text on a LCD screen which consists of multiple tiny liquid crystal cells (three per pixel) where the material quickly reacts to an imposed electric field when you move the mouse. During my PhD at the University of Bayretuth under the supervision of Prof Rheberg, the response of a liquid crystal to an electric field was investigated in three particular cases: domain walls with and without (electrical) convection and the switching behavior of a cholesteric gel. New transitions to ordered structures were uncovered, showing interesting patterns (like the one in the picture above). You can see some movies showing a different state here.