HIGH-FIELD MAGNETIZATION OF MAGNETIC LIQUIDS CONTAINING AMORPHOUS IRON-CARBON PARTICLES

We have measured the magnetization of magnetic liquids containing amorphous iron-carbon particles with diameters 3.2, 3.8 and 5.0 nm, in fields from 2 to 12 T and at temperatures from 50 to 290 K. The high-field magnetization increases nearly linearly with the field. The differential high-field susceptibility, chi, is practically temperature independent within the measured temperature range and is proportional to the spontaneous saturation magnetization of the magnetic liquids. Chi is of the order of 10(-4) for a magnetic liquid with spontaneous saturation magnetization 10 kA m-1. We interpret the high-field susceptibility as due to the amorphous structure of the particles.