Kerr effect investigations in a liquid crystal

Measurements are reported for the d.c. Kerr response and the pretransitional behaviour of a new liquid crystal, 4-cyanophenyl 4-pentylbenzoate at and above the nematic-isotropic phase transition temperature. The real parts of the third order nonlinear susceptibilities chi((3)) at and above the nematic-isotropic transition temperatures are determined for the new liquid crystal from the electro-optic Kerr effect (EOKE) experiments. The variation of the Kerr constant with temperature is discussed on the basis of the Landau-de Gennes model of the nematic-isotropic phase transition. The susceptibility values are also compared with that of the well known liquid crystal 4'-pentyl-4-cyanobiphenyl (5CB). The effect of the linking group of the liquid crystal on the suceptibility value is also discussed.