The influence of electric dc fields on spontaneously aligned doped films of the nematic liquid crystal anisylidene-$p-n$-butylaniline was investigated. Prior to the application of the field films were uniaxial with the optic axis normal to the substrate; under the influence of a field applied perpendicular to the optic axis films became biaxial. The magnitude of the induced retardation was measured as a function of field strength, and found to increase linearly with $E^2$.

• Received 19 October 1970

DOI:https://doi.org/10.1103/PhysRevLett.25.1326