Dynamic Adhesive Instability of Sub-Five Nanometer Head-Disk Interfaces

Understanding of dynamic adhesive, contact and friction interactions and associated instabilities at magnetic storage head-disk interfaces (HDIs) is critical as the physical distance between the recording slider and the high-speed rotating disk decreases to sub-five nanometers to achieve 155 Gbit/cm² (1 Tbit/in²) recording densities. In this study, a two degree-of-freedom nonlinear dynamic model that includes realistic roughness, adhesion, friction and the dynamics of a flying and contacting HDI was developed to characterize a fully flying (6.8 nm) and a pseudo-contacting (3 nm) HDI utilizing different air-bearing designs. The effect of roughness on the slider flying performance and stability was also investigated through a comparison to a simple two flat parallel surface counterpart. The simulation results revealed that while adhesion has little influence in a fully flying interface when flying heights are above 5 nm, it leads to prolonged contact, higher bouncing vibrations and unstable slider behavior for 3 nm flying height. At such low nominal flying height, the inclusion of the electrostatic force also exacerbates HDI unstable behavior