Observation of One-dimensional Spinodal Decomposition in a Liquid Crystal

点击翻译按钮获取中文摘要

The zigzag instability coarsening of a splay-bend wall formed in a nematic liquid crystal under external fields is investigated experimentally as a study of a one-dimensional analog of the spinodal decomposition in a conserved order parameter system. When an electric field is applied on the liquid crystal, a sinusoidal modulation first appears, then the shape of wall changes to zigzag. In the late stage, the coarsening of zigzag vertexes proceeds due to the coalescence of zigzag vertexes.1.In the late stage of coarsening, a characteristic length, i.e.the mean width of the zigzag period, shows logarithmic increase in time, which agrees with the theoretical prediction.2.The structure function and the correlation function for the Ising domain and the density correlation of zinzag vertexes are analyzed. Then it is clarified that the dynamical scaling law holds in the late stage of coarsening.3.The kink-antikink kinetics of one-dimensional phase ordering is studied numerically. The logarithmic growth of the mean width of domains is also confirmed. The distribution of domain size and the correlation function are shown to satisfy a scaling relation. The two-time autocorrelation function follows a power law whose exponent depends on the start time of the calculation.4.The time evolution of the sinusoidal modulation in the early stage of coarsening is analyzed experimentally. It is found that the sinusoidal modulation develops exponentially up to an equilibrium value as expected in the theory of spinodal decomposition. Basing our study on the linear stability analysis of the splay-bend wall equation of motion, the growth rate of the sinusoidal modulation is discussed. In the vicinity of the zigzag instability, the experimental result agrees with the prediction form the linear stability analysis.