INFLUENCE OF CR CONCENTRATION ON RECORDING CHARACTERISTICS OF CO-CR MEDIA

Investigating the optimum Cr concentration for single layer Co100-xCx media with high storage capabilities, we have prepared 300 nm thick layers with x = 11–34 at. % Cr by co-evaporation on polyimide substrates. The values of MS, Δθ, Hk and HC(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 1/2” flexible disks, protected by a 40 nm thick sputtered a-C layer, give clear evidence of a change of the recording mode at ∼ at. % Cr. Only for higher x the preferred perpendicular recording signal is obtained. Due to the use of ring heads the D50 values show a strong correlation with Hk, whereas no obvious correlation with Δθ and HC (perpen) is found. For Cr concentrations > 25 at. % D50 values of more than 90 kfci are obtained. © 1990 IEEE