Direct measurement of lubricant relaxation on a disk surface

This paper presents a novel method for studying the relaxation characteristics of a molecularly thin lubricant film. The thickness dependent diffusion constant is measured by monitoring the temporal decay of a lubricant film thickness with a well-controlled initial sinusoidal thickness modulation. The lubricant film thickness can also be modulated by flying a slider in seek mode, creating a 2D "mogul" pattern. Using the previously measured diffusion coefficients, the relaxation of these moguls is simulated and compared with the experimental relaxation images obtained with an Optical Surface Analyzer.