Magnetic force microscopy analysis of the micromagnetization mode of double-layered perpendicular magnetic recording media

The micromagnetization mode of double-layered (DL) perpendicular magnetic recording (PMR) media, as well as the single-layered one, was investigated by a magnetic force microscopy (MFM) in order to clarify the origin of their recording characteristics. The DL media were flexible disks consisting of a CoNiReP PMR layer and a CoB (soft magnetic) or CoNiP (hard magnetic) underlayer, which were recorded using a ring-type head. Due to the variation in the underlayer characteristics, a clear difference in the stray field gradient at the transition region of the recorded magnetization was observed for the first time, which proved the validity of the presumed model for their magnetization mode. Such a direct analysis of the micromagnetization mode is possible only by MFM, and this technique is considered to be indispensable for optimizing the total design of PMR systems.