Novel sputtering process to reduce the grain size and its distribution in Co-based longitudinal thin film media-new seedlayer and high KuGrain material

To reduce the grain size and its distribution, two kinds of new techniques have been introduced. In the first one, a new WCr seedlayer combined with dry-etching process was found to be effective in reducing the grain size of the magnetic layer while maintaining the intergranular magnetic interactions. As a result, the media signal to noise ratio is significantly increased. In the second one, the usage of a Co co-precipitated NiP/Al plated layer combined with dry-etching and oxygen exposure processes was found to be effective to increase the media signal to noise ratio while maintaining the resolution and coercivity. A new ternary magnetic alloy of Co-Ge-Cr (85 at.% Co, 10 at.% Ge, 5 at.% Cr) was found to have the following magnetic properties: K_u ^Grain=3×10⁶ erg/cm³, H_k^grain=10 kOe and 4πM_k/H_k^grain<1.0. This new magnetic material is a very promising candidate for use in high-density magnetic recording media