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.