Reversible Transition between Topologically Equivalent States in a Chiral Liquid Crystal with Negative Dielectric Anisotropy

In a layer of a chiral liquid crystal with negative dielectric anisotropy and the thickness d corresponding to the second Grandjean zone ( $$3{{p}_{0}}{\text{/}}4 < d < 5{{p}_{0}}{\text{/}}4$$ , where $${{p}_{0}}$$ is the natural helical pitch) under the action of a planar electric field, an orientational transition occurs from the ground state twisted by the angle $$2\pi $$ to a topologically equivalent untwisted state (0 state). Although the 0 state is metastable and long-lived, it can rapidly be transformed back to the $$2\pi $$ state by an electric field pulse of a comparatively small amplitude. The direct transition to the 0 state is induced by the interaction of the electric field with negative dielectric anisotropy, while the rapid reverse transition can be attributed to the flexoelectric interaction.