Giant magnetic coercivity and percolation effects in granular Fe-(SiO2) solids

Abstract

We demonstrate a novel method for enhancing the coercivity of magnetic materials. Granular Fe-(SiO2) solids have been fabricated over a wide volume fraction range from 15% to 100%. Giant magnetic coercivity, as high as 2500 Oe, has been observed in granular solids in which the isolated Fe granules are only nanometers in size. Across the whole volume fraction range magnetic coercivity experiences dramatic variations due to the change of granular size and percolation effects.