We report on chevrons (herringbonelike patterns) observed in homeotropically aligned liquid crystals with high electric conductivity. We focus our attention on two types of chevrons observed in the conduction regime. The threshold voltage and the characteristic double periodicity of chevrons (i.e., the short wavelength ${\lambda }_1$ of the striated rolls and the long wavelength ${\lambda }_2$ of the chevron bands) have been measured as functions of the applied electric frequency f. With the aid of a crossed polarizer set, we have, in addition, determined the director field which shows a periodic in-plane rotation for our chevrons (with a wavelength ${\lambda }_2).\mathrm{}$ We arrived at the types of chevrons after qualitatively different bifurcation sequences with increasing voltage. The frequency dependence of ${\lambda }_2$ also shows a qualitatively different behavior with respect to the two types of chevrons. The experimental results are discussed in terms of recent theoretical investigations.

• Received 24 May 1999

DOI:https://doi.org/10.1103/PhysRevE.61.2769