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 soft magnetic underlayer, such as a permalloy film, was inserted between a Co-Cr recording layer and a substrate. According to our evaluation using a ring-type head. the reproduced output of a Co-Cr medium was greatly increased by the existence of the above very thin (∼10 nm) soft magnetic underlayer without giving rise to any deterioration in its high density recording characteristics. It is considered that this increase of the reproduced output is due to the decrease of demagnetizing field acting on recorded magnetization which was caused by the establishment of horse-shoe magnetization modes in the vicinity of recording transition regions.