Slider dynamics during continuous contact with textured and smooth disks in ultra low flying height

Abstract

Dynamics of a nano-slider during continuous contact with textured and smooth disks are studied using laser Doppler vibrometer, friction sensor, acoustic emission (AE) transducer and read back signal from a magneto-resistive head on the slider. The flying height of the slider is controlled from flying to contact at the same velocity by changing the environmental pressure. When the slider flies over the textured disk, contact occurs at flying height of 14 nm, and friction and AE signal increase gradually with decreasing flying height. The increase in the amplitude of the slider vibration is within a few nanometers from flying to contact. When the slider flies over the smooth disk, contact occurs at much lower flying height of 6 nm. However, friction, AE signal and the amplitude of the vibration show a steep increase upon contact. Both pitch and roll vibration modes of the slider air bearing are strongly excited with amplitude of about 10 nm. The pitch vibration results in the slider impacting the disk surface severely. As a result, the disk vibrates at the same frequency. In addition, thermal asperities with extraordinarily high amplitude are observed associated with the impacts induced by the pitch vibration.