Effects of NiFe Underlayer on the Properties of CoCr Layer in Perpendicular Double-Layered Media

CoCr/NiFe double-layered perpendicular media were sputter-deposited onto NiP-plated aluminum substrates. The crystal orientation and magnetic properties of the CoCr layer on NiFe are poorer than those of CoCr on Nip. In order to improve the properties of CoCr/NiFe film, the effects of the NiFe underlayer were investigated with respect to the surface roughness, crystal orientation and crystallinity. It was found that the crystallinity of the NiFe layer strongly affects the crystal orientation of the CoCr layer. Both bias sputtering and a low residual gas pressure were effective for improving the NiFe crystallinity. The c-axis dispersion angle (¿ ¿50) was as small as 1.6° for CoCr on a highly crystalline NiFe layer.