Physical effects of the surface elastic term K₁₃ on weak anchoring nematic liquid crystal cells

Abstract

This paper aims at providing me1hods of checking whether the surface elastic term K ₁₃ exists or not, by studying the physical effects caused by K ₁₃ on weak anchoring planar NLC cells. We adopt the effective expression of K ₁₃ for an ideal surface according to Pergamenshchik and Žumer, and obtain the following results. (1) can be determined by two threshold fields if both the Fréedericksz transitions at the threshold point are of second order. One threshold field corresponds to application of the external magnetic field perpendicular to the substrates; the other corresponds to the field parallel to the substrates. (2) The existence of the K ₁₃ term may change the property of the Fréedericksz transition, i.e. from first order to second order, or vice versa. (3) The various curves of relative optical retardation versus reduced magnetic field h for different k intersect at one point, and the slopes at the common point are sensitive to k. These results assist in the design of experiments to check the existence of K ₁₃.