Dynamics of a faceted nematic-smectic B front in thin-sample directional solidification
Abstract
We present an experimental study of the directional-solidification patterns of a nematic - smectic B front. The chosen system is C_4H_9-(C_6H_{10})_2CN (in short, CCH4) in 12 \mu m-thick samples, and in the planar configuration (director parallel to the plane of the sample). The nematic - smectic B interface presents a facet in one direction -- the direction parallel to the smectic layers -- and is otherwise rough, and devoid of forbidden directions. We measure the Mullins-Sekerka instability threshold and establish the morphology diagram of the system as a function of the solidification rate V and the angle theta_{0} between the facet and the isotherms. We focus on the phenomena occurring immediately above the instability threshold when theta_{0} is neither very small nor close to 90^{o}. Under these conditions we observe drifting shallow cells and a new type of solitary wave, called "faceton", which consists essentially of an isolated macroscopic facet traveling laterally at such a velocity that its growth rate with respect to the liquid is small. Facetons may propagate either in a stationary, or an oscillatory way. The detailed study of their dynamics casts light on the microscopic growth mechanisms of the facets in this system.
Cite
@article{arxiv.cond-mat/0109148,
title = {Dynamics of a faceted nematic-smectic B front in thin-sample directional solidification},
author = {T. Borzsonyi and S. Akamatsu and G. Faivre},
journal= {arXiv preprint arXiv:cond-mat/0109148},
year = {2015}
}
Comments
12 pages, 19 figures, submitted to Phys. Rev. E