Development of Fe_<16>N_2 Ultra Fine Particles for High Density Recording Media

Abstract

For high density recording media, Fe_<16>N_2 fine particles were developed using co-precipitation and nitridation treatment in NH_3 gas atmosphere. Each particle has a spherical shape with a diameter of about 18nm and core-shell structure. The core and shell mainly consist of the Fe_<16>N_2 and non-magnetic oxides. The coercive force is higher than that of the needle-shaped metal particles currently used an disstable from room temperature to 323K. The higher coercive force originates from an uniaxial magneto crystalline an isotropy of the Fe_<16>N_2. We have per formed polarized neutron scattering experiments of the Fe_<16>N_2 fine particles. The magnetic moment of the Fe_<16>N_2 and the thickness of the non-magnetic surface layer were estimated to be about 2μ_B/ Featom and 3nm, respectively.