Flying-height reduction of magnetic head slider due to thermal protrusion

The current flying heights of the magnetic head sliders in hard disk drives are approximately 10 nm. Under such low-flying-height conditions, however, both the heat generated by the current in the write coil and the rise in the ambient temperature can cause local protrusion of the head elements. Such thermal protrusion (TP) reduces the flying height below the design value, thus reducing the safety margin for the head/disk interference. The purpose of this work was to numerically simulate the TP and obtain head design guidelines based on the simulation results. In addition, actual reduction of flying height due to the TP was simulated.