Effect of Collective Molecular Reorientations on Brownian Motion of Colloids in Nematic Liquid Crystal

• DOI: 10.1126/science.1240591
• Publication Date: 2013-12-12T19:16:18Z
• Authors: T. Turiv; I. Lazo; A. Brodin; B. I. Lev; V. Reiffenrath; V. G. Nazarenko; O. D. Lavrentovich
• Keywords: Mean squared displacement; Anomalous Diffusion; Brownian dynamics

In the simplest realization of Brownian motion, a colloidal sphere moves randomly in an isotropic fluid; its mean squared displacement (MSD) grows linearly with time $\textitτ$. motion orientationally ordered fluid, nematic, is anisotropic, MSD being larger along axis molecular orientation, called director. We show that at short scales, anisotropic diffusion nematic becomes also anomalous, growing slower (subdiffusion) and faster (superdiffusion) than The anomalous occurs scales correspond to relaxation times director deformations around sphere. Once melts, normal isotropic. experiment shows fluctuations long-range orientational order profoundly influence diffusive regimes.