Investigation of head-disc dynamics with laser pattern simulated disc microwaviness

As the fly height requirement for ultrahigh density magnetic recording becomes more stringent, the control of head media spacing (HMS) modulation becomes extremely critical not only for the reliability of the head-disc interface but also for magnetic read/write performance. Disc topographical features with lateral dimensions ranging from 10% to 80% of the slider length are known as microwaviness, and these features can have a profound influence on HMS modulation. In this work, we demonstrate that disc microwaviness can be simulated by laser texture patterns. The controllability of such simulated “microwaviness”, in terms of frequency, amplitude and aspect ratio, makes this technique particularly powerful to gain fundamental understanding of the effect of disc microwaviness on the HMS modulation. It was found that when the laser pattern frequency intercepts the air bearing frequency, the resulting resonance induces severe HMS modulation. The response is a linear function of head-disc spacing, and the effect of spacing modulation becomes much more pronounced at higher laser bump heights