Effects of thin carbon intermediate layer on magnetic and structural properties of perpendicular recording media

CoCrPt/CoCr/carbon films were sputter-deposited on CoTaZr soft-magnetic underlayers and the effects of a carbon intermediate layer on magnetic and recording properties were investigated by changing a heating sequence in sample preparations. A heating process before a CoCr deposition was needed to obtain a high perpendicular coercivity. The carbon diffusion into a CoCr layer during its deposition led to small crystal grains in the CoCr layer and thereby the CoCrPt layer. Consequently, a high perpendicular coercivity was obtained, which was considered due to the change in magnetization process from a wall motion to a coherent rotation. The use of a thin (1–5 nm) carbon intermediate layer was found to be effective to obtain both low noise and high resolution.