Qingfang Leng

Flying height-attitude observation and investigation of sliders in load/unload process

A novel flying height-attitude testing system was developed based on white-light interferometry. Flying heights at three desired locations on the slider surface can be determined simultaneously with this system and, thus, slider attitude can be fully determined from the measurement results. Load and unload processes were systematically studied with this system and some details were revealed.

An experimental study of slider vibration in nanometer spaced head-disk interface

This paper reports results of experimental investigations into slider-disk interaction and slider vibration in nanometer spaced head-disk interface. The investigations were based on an slider-disk interface (HDI) configuration which retains the tribological features of the interface formed by the functional head slider and disk media but make the optical monitoring and quantitative measuring of the slider disk spacing possible. The effects of the lubricant and its thickness on the HDI dynamics were also studied. The results indicate that the slider vibration is dependent not only on slider air-bearing surface design but also strongly on lubricant and other interface conditions.

Slider-disk interaction and its effect on the flying performance of slider

This paper reports a novel optical head-disk interaction tester setup and experimental investigations into the effects of slider-disk interaction in nanometer spaced head-disk interface. The setup revealed quantitatively the lubricant induced change of slider-disk spacing before the slider enters its fully flying status. The setup was also applied to investigate the slider sinking process which is caused by the meniscus force when the slider starts to rest on disk surface. Results shows that such a setup has the advantage of quantitative characterization of slider-disk interface compared with acoustic emission method. Furthermore, the results also demonstrate its advantages in reflecting the actual interaction between slider, lube, and disk surface, compared with the current optical flying height testers.

Bump characterization with MR/GMR head as transducer

With a magneto-resistive (MR) head as transducer, this paper report a method and experimental results of fast in-situ characterization of laser textured bumps over disk surface. The thermally induced change of the resistance of MR head is used to conduct fast analysis of the uniformity of bump width, bump pitch interval, and bump height in the laser textured landing zone of a magnetic disk. Two modes of the tester setup are discussed. One mode is for the fast detection of the above mentioned uniformity within one disk revolution. Another mode is for mapping the selected bumps or all the bumps in a selected sector or a sub-zone of the textured landing zone. The setup can be used in both on-line and off-line analysis of the laser bump uniformity in media manufacturing process.

Scanning carrier current method for in-situ measurement of flying height variation

A novel writing process based in-situ flying height measurement method, scanning carrier current method, is proposed. An erasure current oscillating in the frequency range of 200/spl sim/800 kHz is injected to the write head during the period of interest. Later, its effect on previously written data is detected to infer the flying height during the period of interest. The maximum scanning carrier current method provides a good solution to measure flying height variation in a large range during dynamic transient process. When the slider is in steady flying status, a lower scanning carrier current method can reduce the noise caused by medias MrT fluctuation, whilst a biased scanning carrier current method is suitable to reduce the noise caused by medias coercivity fluctuation in the flying height testing process.

Height-attitude observation and investigations in load/unload processes

Summary form only given. Further reduction of magnetic head-disk spacing towards 8/spl sim/10 nm will require proper testing tools for in-depth experimental analysis of 3 dimensional dynamic stability of the slider in both the track following process and the load/unload process. The authors proposed and developed a novel flying height-attitude testing system that measures flying height simultaneously at three desired locations on the slider surface.