Time-resolved X-Ray Scattering Studies of Reversible Layer Flexing in a Surface Stabilised Ferroelectric Liquid Crystal Device

Recent time resolved x-ray scattering studies of a surface stabilised ferroelectric liquid crystal (SSFLC) device have demonstrated that the smectic layers move in two orthogonal planes during low field switching of the device. This paper extends our initial studies of the layer motion and presents a detailed examination of the influence of low field switching on the chevron layer structures in a 3 μm SSFLC device. A symmetric bipolar pulse was applied to the device at a temperature 5°C below the ferroelectric chiral smectic-C to smectic-A phase transition. X-ray scattering data, corresponding to the intensity and position of the Bragg peak, were collected with microsecond time resolution. Results are presented which show a rapid, reversible flexing of the smectic layers to much lower angles during switching with fields of magnitude ±3 Vμm−1 followed, in some cases, by a slow (millisecond) return to the original layer structure. The data are to some extent consistent with the layer flex model proposed by Gießelmann, followed by domain motion within the device.