Nonlinear dynamic effects at the head-disk interface

The contact dynamics of pico sliders is investigated using a high bandwidth laser Doppler vibrometer (LDV) and a high bandwidth acoustic emission (AE) sensor. Sliding contact of the slider near the glide avalanche point is analyzed for a lubricant thickness of 1.5 nm, 2.5 nm, and 3.5 nm, respectively. Slider airbearing modes as well as torsional and bending mode vibrations are investigated as a function of disk velocity and lubricant thickness. Damping of the airbearing pitch and roll frequency is found to increase with increased lubricant thickness. Nonlinear slider/lubricant interactions are observed leading to additional peaks in the LDV spectrum near the bending mode frequency. Nonlinear effects due to slider/lubricant interactions are modeled using a nonlinear stiffness term in the equation of motion. The numerical and experimental results are found to be in good agreement.