Study of head-disk interaction and spacing based on readback signal

Based on amplitude modulation and frequency modulation analyses of the readback signal of a single-tone frequency pattern, the slider´s down-track positional and fly height modulation amplitudes can be determined. We show that the slider´s flying behavior undergoes through three distinct regimes as the fly height is decreased via thermal fly height control: stable flying at clearance, unstable flying or bouncing contact following the onset of touch-down, and stable sliding in the deep interference state. A minimum head-medium spacing and maximum recording performance are achieved in the deep interference state as a result of the lubricant being squeezed out of the head-disk contact.