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To achieve the areal density goal in hard disk drives of 1 Tb/ [in.sup.2] the minimum physical spacing or flying height (FH) between the read/write transducer and disk must be reduced to about 2 nm. At such low spacing new nanoscale forces act between the slider and disk, such as intermolecular and electrostatic forces, which must be taken into consideration in the air bearing design. These forces increase the level of flying height modulations (FHMs), which in turn creates dynamic instability and intermittent contact in the flying head slider similar to what has been observed in experiments. Here, we present three possible approaches to minimize such forces and/or reduce FHM by FH control, including a micro-trailing pad slider, a thermal flying height control slider, and a piezoelectric flying height control slider for hard disk drives. Index Terms--Air-bearing surface (ABS), electrostatic forces, flying height (FH), flying height modulation (FHM), head-disk interface, inter-molecular forces, piezoelectric flying height control, thermal flying height control (TFC).

A system approach for designing the channel path of disk drives is required for achieving high data rates and maintaining data integrity. The channel path includes electronics, electrical interconnects, and the read/write heads. The signal transfer through electrical interconnects is affected by its physical components that create the losses and the termination effects. From electromagnetic analysis or measurements, s-parameters are obtained for analyzing signal transfer and crosstalk. Using these s-parameters, chain type matrices can be created to apply an efficient system analysis of the signal transfer. This type of system analysis can be used to produce frequency and time domain response of the complete channel path: read/write transducers, suspension interconnect, read/write IC, flex interconnect, and channel IC. Index Terms--Chain matrix, electrical interconnect, preamplifier, read/write electronics, s-parameters, write driver.

Reduction of interactive force between magnetic head and hard disk is an important issue for maintaining the ultra-low spacing required for ultra-high recording density. The spacing would be below 5 nm for 1 Tb/[in.sup.2] density. In this study, the head-disk interactive force was examined when monofunctional lubricant (that with a functional group only at one end) and difunctional lubricant (that with functional groups at both ends) were used, respectively. The study has revealed that usage of monofunctional lubricants effectively reduces the head-disk adhesive interaction at near-contact operation. Index Terms--Hard disk, head-disk interface (HDI), interaction force, lubricant, take-off, touch-down.

We report on the investigation of electrostatic discharge (ESD) sensitivity of current perpendicular to plane (CPP) magnetic tunnel junction (MTJ) heads used in hard disk drives (HDD). Our results show that MTJs have different degradation characteristics and mechanisms from current in-plane (CIP) giant magnetoresistive (GMR) heads when exposed to cumulative ESD current transients. Both MTJ and GMR heads show gradual amplitude degradation as a result of increasing ESD levels, but MTJs are more robust than GMR heads in terms of sensor stack magnetic stability, such as polarity flip. Large ESD voltages could change stability state of the MTJ heads, which shows up as random telegraph noise associated with transfer curve magnetic distortions in low-frequency regime and noise spikes several times above baseline noise in high-frequency regime. This MTJ instability is likely a result of defects in the multilayer reader magnetics and disturbances, as well as degradation of tunnel oxide barrier. Index Terms--Electrostatics, magnetic heads, noise, tunnel junctions.