Friction and adhesion forces on magnetic disk surfaces

Distributions of friction and adhesion forces between magnetic disk surfaces and tips have been measured with high accuracy. When the frictional force between a very sharp tip and a nonlubricated disk is measured, stick-slip motions are observed. Lubrication prevents these motions and lowers frictional coefficients. When adhesion force is measured, several sharp peaks are observed for nonlubricated surfaces. Lubrication lowers these peaks and flattens slopes. These high-accuracy measurements verify that disk surfaces are not homogeneous and that lubricants act to homogenize friction and adhesion force distributions on disk surfaces