Defect inspection method for perpendicular magnetic recording medium, magnetic disk device, and method of registering defects in magnetic disk device having a perpendicular magnetic recording medium therein

摘要

Because of its characteristics, a perpendicular magnetic recording medium has the inconvenience that since sections with low signal stability due to magnetic defects are not easily detectible in advance, these sections are detected after mounting of the medium in a magnetic disk device or after product shipping. According to one embodiment, in the manufacturing processes for the perpendicular magnetic recording medium, a DC-erase process step for direct-current demagnetizing the medium is performed after a magnetic film deposition process step and a lubricating-agent application process step. This maximizes the effects of a demagnetizing field and intentionally increases directional instability of magnetization. After the above processes, the medium is further provided with a heating process to accelerate the reversal of magnetization in latent defective sections. A defect examination step for detecting the magnetization reversal sections on the basis of changes in the baseline of the signal read out from the medium under the above state is performed, whereby defects can be detected efficiently.