Slider Overcoats for Enhanced Interface Durability in Magnetic Recording Applications," presented at the ASME/ STLE Tribology Conference,

Introduction In a magnetic recording disk drive, recording is achieved by the relative motion between a slider, containing a read/write magnetic transducer (the head), and a rigid disk, which contains a magnetic recording medium. Relative motion is achieved by spinning the disk up to very high angular velocities. The slider is designed such that as the disk angular velocity increases, a thin hydrodynamic air bearing develops between the slider and the disk. This air bearing prevents contact between the slider and disk during operation, and greatly increases the life and durability of the head/disk interface. One of the more crucial factors contributing to a limitation in the linear storage density is the flying height, defined as the spacing between the head and the disk generated by the air bearing when the disk is at its full operational speed. In stateof-the-art disk drives, the spacing between the two has been reduced to as little as 50 nanometers (2 microin.). Perhaps the most important limiting consideration in further lowering the flying height is the tribology of the head disk interface. In general, a lower flying height implies that the slider maintains sliding contact with the disk for longer distances prior to "takeoff" and after "landing." In addition, a lower flying height results in an increased incidence of contact between the head and disk during flying. The friction and wear characteristics of the slider/disk interface depend to a large extent on the nature of the materials at the interface. The disk industry commonly uses a layer of carbon, typically 20-30 nm thick, to protect the magnetic medium on the disk. A layer of lubricant 2-3 nm in thickness is then applied to the surface of the carbon overcoat to further reduce friction and wear during operation