The temperature dependence of the reduced anisotropy in magnetic recording particles

The temperature dependence of the reduced anisotropy in acicular magnetic recording particles is found from initial susceptibility measurements between 77 and 420 K. The results give information about the relative contributions to the coercive force from the shape and the magnetocrystalline anisotropy, and the extent to which a sample can be thermally demagnetized. Compositions include ion oxides with differing Fe
²⁺
/Fe
³⁺
ratios; Co-adsorbed and Co-doped iron oxides some of which contain Zn; CrO
2
; and Fe.