Anisotropy Properties of Magnetic Colloidal Materials

Magnetic anisotropy of particulate magnetic materials is investigated with respect to the particle shape and compacting geometry. Uniform sized micro-rods and microspheres, coated with nickel, were used. Our results reveal that uniformly aligned rods show the largest magnetic anisotropy, while the field-oriented suspension of coated micro-rods shows somewhat weaker magnetic anisotropy, which is in excellent quantitative agreement with the theoretical calculation. The magnetic anisotropy drops significantly when the micro-rods were replaced by microspheres, even when they were aligned in chain-like formations.