Electro-optic Kerr effect in the isotropic phase above the columnar phase of a urea derivative

The authors have measured the electro-optic Kerr effect in the isotropic phase of a urea derivative. Electric-field-induced birefringence Δn was observed in the isotropic phase even 30 °C above the isotropic-columnar phase transition temperature. The induced birefringence is inversely proportional to temperature, as predicted by the Landau–de Gennes theory. Two distinct regions are identified from the proportionality constants in the isotropic phase; optical second-harmonic generation (SHG) is easily observable in the low-temperature region on applying an electric field, whereas SHG activity does not emerge in the higher-temperature region. The structure of molecular assemblies is discussed based on these experimental results.