Magnetochromatic effects in magnetic fluid thin films

A homogeneous ferrofluid composition capable of reversibly forming ordered crystalline two-dimensional hexagonal lattices of magnetic particle columns in a thin film under the influence of external magnetic fields has been synthesized. We can manipulate the spacings between the particles columns by adjusting parameters such as external magnetic field strength, film thickness, rate of change of the field strength, and concentration of magnetic particles in the ferrofluid. These spacings between particle columns are of the order of several micrometers and are capable of diffracting visible light to produce monochromatic interference colors. We can change the resulting colors by altering the lattice spacing to exhibit the feasibility of generating monochromatic colors. (C) 1998 Optical Society of America.