Touchdown of Flying Recording Head Sliders on Continuous and Patterned Media

We conduct three-dimensional transient finite-element analysis to study the contact behavior during touchdown detection by a thermal flying-height control (TFC) recording head on continuous and patterned elastic-plastic layered media. The heat generated during touchdown and the plastic strain of the media are calculated in the model. We investigated key factors such as the radius of curvature of the TFC protrusion, media compositions, bit-patterned media (BPM), and the effect of planarization. Our analysis shows that when subjected to the same TFC over-push, BPM is much more likely to result in plastic deformation than the continuous media. The temperature distribution of planarized BPM with ${\hbox{SiO}}_{2}$ as filling material exhibits a complex and distinctive pattern different from the one without planarization. More importantly, the maximum plastic strain of the planarized BPM is 50% larger than the one without planarization, which means that filling with ${\hbox{SiO}}_{2}$ deteriorates the media's robustness to the touchdown probably due to the mismatch of thermal properties between ${\hbox{SiO}}_{2}$ and recording material. This suggests the filling material must be carefully chosen to avoid the excessive plastic strain.