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New methodology to obtain reliable correlation between magnetic cluster details measured using magnetic force microscopy (MFM) and noise in perpendicular recording media is reported. In addition to the ac demagnetized state, which is often studied by several researchers, magnetic clusters were examined at two other magnetic states of the recording medium to obtain details on thermally unstable and relatively nonreversible clusters that would increase noise and bit-error rates. The proposed method was employed to study magnetic clusters of media samples fabricated at different conditions. Measurements on various samples demonstrated that the MFM can be used to understand the thermally unstable and irreversible clusters in a perpendicular recording medium. A direct correlation between the signal-to-noise ratio of the medium measured using spin-stand and magnetic cluster details from MFM images is obtained. The trend can also be used to understand and distinguish the source of noise (such as writing issues or the media microstructure issues). [ABSTRACT FROM PUBLISHER]

Perpendicular recording media technology faces limitation in the writability of media with high anisotropy. Therefore, alternative methods are sought to overcome this problem. Heat-assisted magnetic recording may give rise to high areal densities, but the technological process will take time. We have studied methods to improve the writability in perpendicular recording media using crystalline soft underlayer (C-SUL) materials with fcc(111) texture. One of the recording media designs consists of a simple insertion of C-SUL material between the nonmagnetic intermediate layers, thus providing a path for magnetic flux during the writing. In the alternative methods, part of the nonmagnetic intermediate layer material was replaced with C-SUL material. Overwrite improvement was observed in both the cases, indicating that the C-SUL material will play a major role in improving writability in recording media. [ABSTRACT FROM AUTHOR]