Magneto-chromatic effects of tunable magnetic fluid grating

The ordered structures in Fe3O4 kerosene-based magnetic fluid films were discovered and the magneto-chromatic effects were also observed under various magnetic fields. In this report, we studied the relationship between the ordered structures and the magneto-chromatic effects theoretically and experimentally. The nearly perfect hexagonal structures with the distance between two columns d in mu m range for our magnetic fluid thin films offer a two-dimensional tunable magnetic fluid grating in the visible light region. By using a grating model, the diffraction patterns for visible lights at certain incident angle theta, wavelength lambda, and column distance ct, were calculated. Experimentally, it was found that the conditions of the observed light around the direction perpendicular to the plane of film coincide with the calculated results. Therefore, the magneto-chromatic effects resulting from the ordered structures of the tunable magnetic fluid grating were confined. (C) 1998 American Institute of Physics. [S0021-8979(98)22111-6].