Magnetic and Electric Field Induced Periodic Deformations in Nematics

(Received 17 January 1995, revised 11 August 1995, accepted 21 August 1995)

Abstract
This work reports theoretical studies on the occurence of a static periodic distortion (PD) in a nematic sample under the action of crossed electric (E) and magnetic (H) fields applied on a uniformly aligned initial director configuration (n ). Linear stability analysis with rigid anchoring hypothesis is employed. For homeotropic alignment of a nematic such as M1 which has negative dielectric anisotropy ( ) and positive diamagnetic anisotropy ( ), PD occurs when E and H are both in the sample plane. The direction of periodicity depends on the angle between E and H; PD is unfavorable when H is tilted sufficiently away from E. In a material (such as CCH-7) with and , the direction of periodicity changes continuously in the H, E plane as a function of the strength and tilt of the stabilizing H relative to E. Possible effects of flexoelectricity, weak anchoring and director pretilt are discussed briefly.