Anisotropy and switching behavior of recording media: comparison of barium ferrite and acicular particles

The anisotropy and switching behavior of recording media made with barium ferrite platelets are very different from those of media made with acicular magnetic particles. It was found that the ratio of the anisotropy field to the remanence coercivity increases with the diameter-to-thickness ratio (aspect ratio) of barium ferrite particles and is higher than for acicular particles except for platelets of relatively low aspect ratio. Very strong interparticle interactions, tending to make switching easier when increasing the net magnetization than when decreasing it, are found in all barium ferrite samples studied, but not in acicular materials. These interactions do not appear to depend on the aspect ratio of the barium ferrite particles