Packing-fraction dependence of coercivity of interacting acicular skeleton-particles of α-Fe

Abstract

For fine, acicular skeleton-particles of α-Fe prepared from α-FeOOH, the interparticle interaction effect on packing fraction dependence of Hc was numerically studied under a direct expansion scheme of the “chain-of-spheres” fanning model to an interacting chain system, which forms an orthorhombic type of regular space lattice. It is shown that magnetostatic interchain interactions along the chain axis provide an increase of interaction anisotropy, while the interactions across the chains decrease the anisotropy. Generally, the latter effect on Hc is mathematically more pronounced than that of the former. Consequently, Hc of the many chain system decreases almost always as the packing fraction increases. It is also found that geometrical configuration of the chain location has a very important role in the packing-fraction dependence of Hc. The results compared with experiments revealed good agreement with the data, and it seemed that a formation of a “chain-of-particles” like anisotropic arrangement is realized in magnetically oriented recording media. It was also tried to apply the present model theory to typical published data with respect to an assembly formed by the skeleton type particles of α-Fe or γ-Fe2O3.