Előadó: Salamon Péter (SZFI)
Az előadás témája: Liquid crystal spherical caps in magnetic field
Az előadás időpontja: 2021. január 12., kedd, 10.00
Helyszín: videokonferencia, https://letsmeet.wigner.hu/szeminarium
We investigated the static and dynamic behavior of plano-convex lens shaped droplets of a liquid crystal in the presence of magnetic field by experiments and theoretical calculations . The structure of the average molecular orientation field (the director) was investigated as a function of magnetic field. Polarizing optical microscopy indicated that a disclination line appears inside the droplet, whose localization depends strongly on the tilt angle of magnetic field with respect to the flat base plane. We found dynamical behavior of the defect wall, and studied how the motion of disclination depends on experimental conditions such as the magnitude or direction of the applied magnetic field. The system under scope can be used as a liquid optical lens with light polarization dependent focal length, tunable by magnetic field. Our work reveals the nature of external field induced defect formation that may act adversely in applications, and we show in what conditions the disclination formation can be eliminated.
 P. Salamon, Z. Karaszi, V. Kenderesi, Á. Buka, A. Jákli, Liquid crystal spherical caps in magnetic fields, Phys. Rev. Research 2, 023261 (2020)