Disk surface dynamic coercivity and other surface parameter measurement at spin stand

Dynamic coercivity is one of the major parameters for the media in the hard disk drive. A new method is developed to measure the disk surface dynamic coercivity distribution at spin stand in this paper. The track of the disk is divided into many sectors and each sector is measured by the fitting line with the minimum mean square error method around the track-averaged data. Test condition is important for measurement at various radii since dynamic coercivity shows heavy dependence on signal frequency and linear speed. This technique can be used to analyze the other dynamic parameters on the disk surface.