Surprising dynamics of some cholesteric liquid crystal patterns

Under homeotropic anchoring conditions, the first order nematic-cholesteric phase transition gives rise to localized spatial patterns called cholesteric fingers. In this Letter we describe a new equilibrium structure which, to our knowledge, has never been reported either numerically or analytically, and we investigate its dynamics. This chiral pattern, which has broken the parity symmetry, is found to move when submitted to an ac electric voltage or to a white noise. Our result may explain, at least qualitatively, the recent observations of spontaneous spiral wave formations in cholesteric liquid crystal under the application of an ac electric voltage.