Late-time coarsening dynamics in a nematic liquid crystal

Abstract

We have studied the coarsening dynamics of line defects in the uniaxial nematic liquid crystal 4-cyano-4'-n-pentylbiphenyl, subjected to a rapid pressure jump from the isotropic to the nematic phase. At late times, the density of disclination lines \ensuremath{\rho} is expected to scale with time as \ensuremath{\rho}\ensuremath{\propto}${\mathit{t}}^{\mathrm{\ensuremath{-}}\ensuremath{\nu}}$ with \ensuremath{\nu}=1. We have measured the scaling exponent to be \ensuremath{\nu}=1.02\ifmmode\pm\else\textpm\fi{}0.09 over the region 16160 ${\mathrm{mm}}^{\mathrm{\ensuremath{-}}2}$. In addition, we have measured the collapse of loops consisting of type-1/2 disclination lines. The loop radius r is expected to scale with time as r\ensuremath{\propto}(${\mathit{t}}_{0}$-t${)}^{\mathrm{\ensuremath{\alpha}}}$, where \ensuremath{\alpha}=1/2 and ${\mathit{t}}_{0}$ is the time at which the loop vanishes. We found \ensuremath{\alpha} to be 0.50\ifmmode\pm\else\textpm\fi{}0.03.