Improvement of magnetic properties and crystallinity of Co-Cr/Ni-Fe double-layer with very thin Co/sub 79/Cr/sub 21/ underlayer

A three-step sputtering system for improving the crystallinity of the Ni-Fe backlayer and the c-axis orientation of the Co-Cr recording layer in double-layered perpendicular magnetic recording media is presented. It is found that the Co/sub 79/Cr/sub 21/ ultrathin underlayer with a thickness of only 100 AA was useful for improving the crystallinity of Ni-Fe backlayers without change of their soft magnetism. The Ni/sub 81/Fe/sub 19/ layer grew on the underlayer heteroepitaxially and, in addition, exhibited good orientation of the