Slider Posture Effects on Air Bearing in a Heat-Assisted Magnetic Recording System

This paper reports the effects of slider posture on the slider bearing in a heat-assisted magnetic recording (HAMR) system with the direct simulation Monte Carlo (DSMC) method. In this HAMR system, the heat issues on the slider bearings are assumed to be caused by a heated spot on the disk and/or slider body itself at various pitch angles. The simulation results show that with a heated spot on the disk, the air bearing pressure and air bearing force that acted on the slider surface will increase when the pitch angle becomes larger. It is also found that the bearing force increases with the heated spot size and the effects of a heated spot become more obvious at a larger pitch angle. On the other hand, the slider body temperature is observed to have a noticeable effect on air bearing pressure and force. The smaller pitch angle enlarges the tendency of bearing force variations with the slider temperature and makes the slider more sensitive to its temperature changes. 1. Introduction With the increasing demands for large amount of storage nowadays, higher density recording technologies are required in hard disk drive industry. Heat assisted magnetic recording (HAMR) is one of the promising technologies to push the recording areal density of magnetic disk drives towards 10？Tb/in2 and beyond. An HAMR system requires using a focused laser beam to heat up the media so as to reduce the media coercivity. It makes magnetic writing possible over high anisotropy magnetic media [1]. Performing the laser heating process requires the optimized slider designs integrating with the near field optical system inside for precise heating and recording. The integrated slider with an optical heating device normally requires flying at an extremely low head media spacing, which is only around few nanometers nowadays, to provide a high field at heated spot position for successful recording [2, 3]. With this spacing allowance, the Knudsen number, which represents the level of rarefaction effect in the flow, will be much larger than 1.0 and the flow in the head disk interface region can no longer be assumed as a continuum one. Some modifications of continuum equations with appropriate slip boundary conditions are usually required. However, it is very challenging to study the slider air bearing in a？？HAMR head disk interface with the current modified continuum equations due to the heat transfer issues involved in the HAMR system. Although some previous studies [4–6] proposed some heat transfer models for addressing such problems, these models cannot be used directly with the air