Nanocomposite Co/SiO/sub 2/ soft magnetic materials

Nanocomposite Co/sub x//(SiO/sub 2/)/sub 1-x/ soft magnetic materials with Co volume fractions, x, from 0.4 to 0.9 were synthesized by a wet chemical approach, followed by consolidation into toroidal samples. The powder samples consisted of single-domain Co nanoparticles with the fcc structure, coated by thin amorphous SiO/sub 2/ shells. The measured saturation magnetization was consistent with the expected value from the Co volume fraction, indicating the completion of the chemical reaction. The initial complex permeability value obtained from a toroidal sample showed an essentially flat frequency response from 10 Hz to 240 MHz, with a quality factor greater than 30. The results show that the Co/SiO/sub 2/ nanocomposite system is very promising as a high frequency soft magnetic material.