Advances in magnetic recording materials

Abstract

Magnetic recording is mainly carried out on thin layers that consist of a dispersion of magnetic particles in an organic binder system. These particles are single domains of either γ-Fe2O3 or CrO2, the magnetic anisotropy of which is due to their acicular shape. The recording performance of γ-Fe2O3 coatings have been enhanced considerably in the past five years by improving the particle morphology. Attempts to make the recording quality of iron oxides equal to that of CrO2 by increasing their magnetocrystalline anisotropy by Co-doping failed because of the resultant insufficient physical stability. Taking into account the good morphology of the present CrO2 a further significant increase of recording performance by the architecturing of oxidic materials is not to be expected. Considerable progress, ∼ 6 dB with respect to CrO2, is possible, however, by using well-shaped metallic iron or iron-alloy particles, owing to their much higher saturation magnetization