Highly-Oriented High-Bs Fe-Co Soft Underlayer for High Density Perpendicular Recording Media

Co-Pt based granular films have been investigated as a recording layer for recent perpendicular magnetic recording media. To induce c-axis crystal orientation of the recording layer at room temperature, relatively thick intermediate layers such as Ru and Ru/Pt are used on an amorphous or a granular soft underlayer (SUL). For high density perpendicular recording, it is desirable that the distance between a single-pole head and a SUL is short. Consequently, it is necessary to enhance the crystal orientation and to reduce the film thickness of the intermediate layer. On the other hand, a high-Bs SUL is needed to reduce the film thickness from the viewpoint of industrial production. I tried to prepare an Fe-Co soft underlayer with a high-Bs of 2.4 T and a high crystal orientation to solve these problems simultaneously.