Pole-tip protrusion effect on head-disk interface at low flying clearance

With the increase in the areal recording density on hard disk drives, head flying height is quickly dropping below 10 nm. The actual flying clearance of the head above the media surface during read-write operation is farther reduced by write-current induced pole-tip protrusion (PTP). At such a low flying height, the amount of PTP become a critical factor affecting head-disk interface tribology, especially in the areas of interface fly-ability and lubricant transfer from disk to head. This paper presents a new approach utilizing controlled PTP with acoustic emission sensing to study the head-disk interaction at close proximity flying. Actual flying clearance can be measured and controlled through this technique. The PTP contact hysteresis of surfaces with different is compared. With fixed flying clearance, the effects of PTP protrusion to disk lubricant redistribution and lubricant transfer from disk to head are reported.