Reverse dc erase medium noise analysis on exchange-coupling effect in coupled granular/continuous perpendicular recording media J. Appl. Phys. 93, 7855 (2003); 10.1063/1.1557757 Effects of intermediate layers on magnetic properties and read/write performance in CoCrPt perpendicular recording media with an FeHfN soft magnetic underlayerThe spatial distribution of the magnetic reversal field ͑MRF͒ 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.