Temperature induced anchoring transition in nematic liquid crystals with two-fold degenerate alignment

The two-fold degenerate alignment of nematic liquid crystals provided by obliquely evaporated SiOx layers was studied as a function of temperature. A temperature induced anchoring transition from tilted to planar alignment with more than 80 degrees between their preferred directions was found. The director in the two-fold degenerate region seems to follow a circular sector from the uniform tilted to the uniform planar anchoring, as the temperature increases. The anchoring transition is reversible and reveals the existing coupling between the azimuthal and polar angles of the preferred directions of alignment. The applicability of the two-fold degenerate alignment and related anchoring transitions of nematic liquid crystals for devices is briefly discussed.