Influence of Electric and Magnetic Fields on the Molecular Alignment in the Liquid Crystal Anisal-p-aminoazobenzene

The molecular alignment has been studied for anisal-p-aminoazobenzene in the presence of external magnetic and ac electric fields. Measurements of the dielectric loss at a microwave frequency of 24 kMc/sec were used to indicate the extent of the molecular alignment. For the external fields parallel to each other, the degree of molecular alignment which could be obtained for a 370 kc/sec electric field was the same as that which could be produced by a magnetic field. For the magnetic and electric fields perpendicular to each other, the ratio of E/H corresponding to a random orientation of the molecules in the plane of E and H was obtained. As the magnetic field was changed from 500 to 3000 G the ratio of E/H remained constant within the limits of experimental error. The value obtained for E/H could not be explained by assuming that the processes responsible for the molecular alignment were associated with only the anisotropy in the dielectric constant and the permeability.