Dynamics of Annihilation Process of Disclination Pairs in Nematic Liquid Crystals

Abstract

We investigated the dynamics of annihilation process of a defect pair in the nematic phase which were generated as type-1 wedge disclinations by quenching the isotropic phase. We measured the time dependence of the distance between a defect pair with or without external electric field. The distance decreased linearly with time immediately after the defect pair was generated (the early stage) and then decreased to zero in proportion to the square root of the time to elapse before the defect pair was annihilated (the late stage). We also treated the annihilation dynamics by numerical simulation with a twodimensional phenomenological equation of motion, and the simulation results were in good agreement with the experimental ones. The ratio of the coefficient of viscosity to that of elasticity and the strength of ordering field were evaluated from the comparison between the simulation and experimental results.

Annihilation dynamics of stringlike topological defects in a nematic lyotropic liquid crystal

“…As we shall see in the discussion, numerical simulations and experimental results for liquid crystals [9,10,11,12,14,15,16,17,26,27,28,29,30,31,32,33,34,35,36,37] support that the annihilation defect-antidefect is well adjusted by the scaling law…”

“…Much of the reported experimental work about the annihilation of defects [8,9,10,11,12,15,28,31,32,34,42,43] was made using thermotropic liquid crystals, where stringlike defects, pointlike defects, and defects loop were analyzed. In thermotropic polyester materials, the annihilation of defects have been observed too [26,29,34].…”

Annihilation of point defect pairs in freely suspended liquid-crystal films

“…1). Models for defect interactions were developed for nematics in one-constant elastic theory [31][32][33], and extended to SmC films [22][23][24][25], where elastic anisotropy [23,24] and dynamic influences [25] were included. The simplest model is derived from linear superposition of single-defect equilibrium solutions of the director field [31].…”

“…During approach, misalignment and mismatch decay to zero, depending on the time until annihilation by a square-root law. The classical theories [23,[31][32][33] remain valid for the special case of aligned, matching pairs. The c-director configurations during the approach are qualitatively similar to quasi-equilibrium states determined from the so-lutions of the Laplace equation [36], but differ quantitatively.…”

Antipersistent behavior of defects in a lyotropic liquid crystal during annihilation

“…In particular, optical textures of liquid crystals [23][24][25] are known to be an excellent system for studying the dynamical behavior of defects. In fact, there are several studies on the annihilation dynamics of defects in liquid crystals employing thermotropics [7,[26][27][28], thermotropic polyester materials [29][30][31] and lyotropic [32]. Moreover, the experimental analysis of annihilation processes has also motivated many numerical simulations [4,6,10,33,34].…”