Flexoelectric origin of oblique rolls with helical flow in electroconvective nematics under DC excitation.

Abstract

We present a 3-dimensional, linear analysis of electrohydrodynamic (EHD) roll instability in a nematic liquid crystal under DC excitation. It is shown that the flexoelectric effect leads to a new symmetry of the flow pattern, viz. a helical flow in oblique rolls. Our experimental observations agree with the theoretical predictions.