Effect of thin-film disk texture on magnetic recording signals

The effect of texturing on the readback signal of Co-alloy thin-film disks is investigated. Instantaneous pulse area (PA) traces, representative of the magnetic signal strength, and instantaneous pulse width (PW50) traces, indicative of the transition resolution, are measured. The low-frequency, "twice-around" modulation is removed from these traces. The resulting PA fluctuations are small; the PW fluctuations are larger and closely correlated to the texture. Calibration of PW vs flying height allows comparison of the texture-induced head clearance modulation and the actual disk surface roughness. The texture causes signal resolution (PW) noise which, for these head/disk combinations, is predominantly due to the spacing loss variations during the readback process. The write process and any texture-related Hc or Mrt fluctuations appear to contribute negligibly.