Theory of orientational modes at a nematic-solid interface When do surface modes appear?

Abstract

Orientational modes at a solid-nematic interface with Rapini-Papoular boundary conditions are analysed in the framework of continuum nematodynamics, including the coupling of the director and fluid velocity. In the case of planar orientation, a surface mode appears in addition to the ordinary bulk modes, if the coupling between the director and fluid velocity, governed by the Leslie coefficient μ₂, is large enough. The dispersion relation for the surface mode exhibits two distinctive regimes as μ₂ increases. In a realistic situation, the relaxation rate of the surface mode is several times slower than that of the corresponding bulk mode.