Influence of Surface Roughness on Durability of Co-Cr Perpendicular Magnetic Recording Medium

Durability of a Co-Cr perpendicular magnetic recording medium was studied with regard to its macroscopic and microscopic surface profiles. Macroscopic deformation of the medium caused by head sliding was investigated with a newly developed measurement system which uses laser light. Also, the microscopic topography of the medium was estimated by spectral analysis of surface profile data. The findings were utilized in observations of head sliding. The medium starts to wear at the sites of protuberances, and the worn portions scratch the medium surface severely. It has been found that the length of durability until the onset of medium deformation is entirely dependent on the initial profile. When the microscopic surface roughness of the medium is so uniform that extraordinary protuberances cannot be observed, the macroscopic medium profile never changes during observations extending for 72,000 head passes, suggesting greater medium durability.