Influence of Cr concentration on recording characteristics of Co-Cr media

Investigating the optimum Cr concentration for single-layer Co_100-xCr_x media with high storage capabilities, the authors have prepared 300-nm-thick layers with x=11-34 at.% Cr by coevaporation on polyimide substrates. The values of M _s, Δθ, H_k, and H _c (perpen) change slowly and continuously with the Cr concentration x. The degree of the perpendicular crystallographic and magnetic orientation increases with Cr content. Recording tests with VHS-type video heads on 3.5-in. flexible disks, protected by a 40-nm-thick sputtered a-C layer, give clear evidence of a change of the recording mode at ~22 at.% Cr. Only for higher x is the preferred perpendicular recording signal obtained. Due to the use of ring heads, the D₅₀ values show a strong correlation with H_k, whereas no obvious correlation with Δθ and H_c (perpen) is found. For Cr concentrations >25 at.%, D₅₀ values of more than 90 kfci are obtained