Intermolecular force, surface roughness, and stability of head-disk interface

Abstract

To achieve 1-Tb∕in.2 magnetic recording areal density, the head/disk spacing, or the flying height (FH) of the slider has to be reduced to 2–3nm and the disk surface roughness and the slider air bearing surface (ABS) roughness need to be well considered when the flying height is in such a regime. This paper presents authors’ efforts in further study of the intermolecular force effects with the surface roughness in consideration and the investigation of the contact force caused by the surface roughness effects. A probability model is built to simulate the intermolecular force and the contact force, and these two forces are introduced into the modified compressible Reynolds equation governing the air bearing pressure of the slider. The simulation results show that the effects of slider/disk roughness on the intermolecular force are negligible. On the other hand, surface roughness plays important roles in the contact force and the contact vibration. Reducing the roughness of both the slider and the disk surfaces is the best solution for reducing the contact force. Moreover, reducing the disk roughness can still significantly reduce the contact force, if the roughness reduction of the slider surface cannot be at the same pace of the disk surface roughness.