Cholesteric cellular patterns with electric-field-controlled line tension

A field-induced instability of wall defects, commonly called oily streaks, is observed in cholesteric liquid crystals. The electric field favors reorientation of cholesteric layers and drives the line tension of the oily streaks negative. Defects with negative line tension elongate, preserving their width. The electrically controlled line tension is a nonmonotonic function of the width; streaks that are too narrow or too wide remain straight. The phenomenon is explained within a coarse-grain model that accounts for the surface anchoring.