Improvement of the reproduced output of Co-Cr thin film media by insertion of very thin soft magnetic underlayer

In order to improve the reproduced output of a Co-Cr perpendicular magnetic recording medium, a very thin (~10 nm) soft magnetic underlayer such as a Permalloy film was inserted between the recording layer and the substrate. An evaluation using a ring-type head showed that the reproduced output of the Co-Cr medium was greatly increased by the underlayer without any deterioration in its high-density recording characteristics. The increase is attributed to the decrease of the demagnetizing field acting on the recorded magnetization, which is caused by the establishment of horseshoe magnetization modes in the vicinity of recording transition regions