Enhanced magneto-optical properties of suspensions of spindle type mono-dispersed hematite nano-particles in liquid crystal

We explored how to increase liquid crystal sensitivity to external magnetic fields. Suspensions consisting of a mixture of liquid crystal and spindle type mono-dispersed hematite nano-particles at concentrations lower than 1 wt% were prepared. The Freacuteedericksz transition threshold for the suspensions appeared to be lower than for the pure liquid crystal. It was proved that adding canted antiferromagnetic nano-particles in liquid crystals increased their sensitivity to magnetic field while no change of the basic mesogenic properties of the matrix occurred

Anchoring and gliding of easy axis of 5CB on photoaligning PVCN-F surface

International audienceAbstract— The photoaligning properties of the popular photoaligning material polyvinyl-4(fluorocinnamate) (PVCN-F) are presented. The aligning quality and azimuthal and zenithal anchoring energy were measured and the drift of the easy orientation axis (gliding effect) on the PVCN-F surface, depending on UV exposure, was studied. Special attention is paid to unraveling the contribution of the adsorption liquid-crystal molecules onto the aligning surface to the anchoring properties of PVCNF and measuring the drift of the easy orientation axis over the PVCN-F surface. It is shown that a relatively weak azimuthal anchoring energy (Waz ∼ 10−7 − 10−5 J/m2) leads to strong drift of the easy axis in the azimuthal plane that was observed in a moderate (∼0.1–0.3 T) magnetic field. A much stronger polar anchoring (Wzen ∼ 10−4 J/m2) allowed us to observe the essential gliding of the easy axis in the zenithal plane in a rather strong electric field (∼5 V/μm)