Lubricant dynamics on a slider: “The waterfall effect”

Abstract

In a modern disk drive, the total slider-to-disk distance, or magnetic spacing, needs to scale with the size of the recorded bit, and nowadays, it amounts to a mere 10nm or less. As disk lubricant often transfers to some extent to the slider surface, it can potentially increase the magnetic spacing. Therefore, it is important to quantify the thickness and flow dynamics of these molecularly thin films on the slider surface. In this paper, modeling, as well as experimental data, is shown that demonstrate the effect on recording performance of a subnanometer thin lubricant layer on the slider. Cleanup by air shear can be predicted reasonably well using the shear map calculated from an air-bearing solver, and reflow by surface diffusion highlights the importance of controlling lubricant transfer from the disk to the slider.