The Influence of an External Electric Field on the Structure of Chiral Sm C∗ Liquid Crystal

Abstract The mechanism of a field induced transition from helical Sm C∗ to Sm C structure in a DOBAMBC liquid crystal situated between two glass plates has been studied by optical methods. The important role of a regular system of twist disclination lines (dechiralization lines) in unwinding the helical structure by electric field has been revealed. A simplified model of ±2π twist disclination pairs is proposed which describes the unwinding of the Sm C∗ structure. Under the external electric field the pairs of ±2π twist disclinations move and annihilate each other and thus effectively unwind the helical structure of the sample. Critical fields for switching the helical Sm C∗ structure, as well as the unwound structure, are estimated.

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