Elasticity of lyotropic chromonic liquid crystal Sunset Yellow probed by magnetic Frederiks transition

By using director reorientation in the magnetic field, we determine the concentration and temperature dependencies of the splay K₁, twist K₂, and bend K₃ elastic constants (normalized by the anisotropy of the diamagnetic susceptibility) for a nematic lyotropic chromonic liquid crystal (LCLC) Sunset Yellow. In a sharp contrast to thermotropic liquid crystals, the Frederiks effects in LCLC show a hysteresis, which is more pronounced at high concentration and low temperatures. We attribute the hysteresis to the changes in self-assembled structure of LCLC aggregates under the influence of field-imposed deformations.