Contents I. Introduction
Molecular rarefaction within gaseous lubricating films is critical to the analysis of the head–disk interface (HDI) as the spacing between the slider and the disk becomes extremely small in order to achieve higher areal recording density. The molecular rarefaction effect was incorporated via the Boltzmann transport equation (BTE) by Fukui and Kaneko [1] and Kang, Crone, and Jhon [2] to describe a slip flow using the Knudsen number (Kn) and surface accommodation coefficient and was implemented to accurately simulate slider attitude. Since the trailing edge fly height is only a few times greater than the lubricant film thickness, it is desirable to invent a rarefied gas dynamics model that can incorporate the molecular information of the lubricant layer. The integrated simulation of the HDI includes the air bearing, lubricant film, and nanoscale heat transfer, which are described by several different length and time scales. A realistic HDI design requires coupling of the component technologies, e.g., the air-bearing stability depends critically on the surface morphology of lubricant film underneath the slider. By adopting advanced surface characterization techniques, we can obtain key parameters (e.g., ) that describe the characteristics of lubricant film simulated via molecular dynamics.
