Magnetic and Electric Field Induced Periodic Deformations in Nematics-Effect of Director Pretilt

Abstract

Using linear stability analysis, theoretical studies are reported on the formation of static periodic distortions (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 ₀). With the rigid anchoring hypothesis, results for director pretilt away from the homeotropic (φ ₀ ≠ 0) reduce to those previously obtained for homeotropic alignment as a special case. Variation of magnetic tilt may lead to discontinuous change in the wavevector of PD. Increase of φ ₀ quenches PD in favour of the aperiodic or homogeneous deformation (HD). Phase diagrams are presented for PD occurring in nematic materials with different types of susceptibility anisotropy.