Magnetic reversal field map combined with medium noise analysis in CoCrPt-SiO_2 granular perpendicular recording medium

摘要

The spatial distribution of the magnetic reversal field (MRF) in a CoCrPt-SiO_2 granular perpendicular recording medium was measured with in-field magnetic force microscopy and combined with the recorded pattern and the medium noise observed at the same location. The areas having low MRF tend to make reverse domains at bit or zigzag transition boundaries, while regions with high MRF do not correlate well with medium noise. The MRF map measured at 20 Oe intervals shows that magnetic reversal occurs mainly in regions adjacent to an already reversed area, suggesting the existence of moderate intergrain exchange couplings. It is concluded that control of the spatial fluctuation of physical parameters such as intergrain exchange interactions, the anisotropy field, grain size, and chemical composition is essential to reduce the medium noise.