Optical anisotropy induced by external magnetic fields on magnetic fluid films

We examined the optical anisotropy of a magnetic fluid film under magnetic fields parallel to the plane of the film by detecting its birefringence eff ect. It was found that the transmission axis of the transmitted light was r otated significantly by an angle Delta eta, with respect to the axis of the linearly polarized incident light when an external magnetic field is appli ed. The angled Delta eta increases with an increase of the field strength a nd then becomes saturated for higher fields. By comparing the detected Delt a eta 's with the corresponding structures formed in the magnetic fluid fil m under various magnetic fields, the angle Delta eta was found to be propor tional to the ratio of the chain area to the liquid area in the film. (C) 2 001 Elsevier Science B.V. All rights reserved.