Kazumasa Fukuda

Edge eliminated head

The authors report that the extra pulses observed in the readback signal of an inductive thin film head can be eliminated by modification of pole tip geometry. The pole surfaces of inductive film head were partially etched by ion milling to reduce the pole length to 0.7 mu m. The etched depth was adjusted to 1 mu m from the pole surface (Type I edge eliminated head). Another modification of the pole tip geometry was also performed. The pole edges were shaped canted to the read/write gap by the same ion mill etching. The angle between the gap and the pole edges was set to 27 deg (Type II edge eliminated head). In both cases of Type I and Type II edge eliminated head, the amplitude of the extra pulses in the readback signal is significantly decreased without reduction of overwrite or any other performance degradation of the head. >

Electrical performance and reliability of tunnel magnetoresistance heads for 100-Gb/in/sup 2/ application

Tunnel magnetoresistance (TuMR) heads are attractive candidates for future high-density recording. To achieve the high areal density, it is necessary for TuMR heads to get lower resistance and higher delta R/R film. A low resistance and high delta R/R tunneling junction film has been developed and used for this study. The resistance area product and delta R/R are 3 /spl Omega//spl middot//spl mu/m/sup 2/ and 18%, respectively. Reliability that includes lifetime was also studied. We have found TuMR heads can be a promising candidate for 100 Gb/in/sup 2/ application.

Write induced instability in spin-valve heads

The output amplitude variation of a spin-valve (SV) head, induced by a write operation, was investigated. The characteristics well depended on the sign of the write current just before a readback process started. It indicated that the write-induced instability should come from a magnetization hysteresis of somewhere magnetic materials. The magnetic core, which consisted of shields and a yoke, was under suspicion as a candidate of the hysteretic origin by sense current, medium and external field excitation tests. Magnetization modeling of a head core revealed a possible mechanism of the instability, which was a shield-related hysteresis.

Low-frequency noise analysis of TMR heads

1/f noise as time traces of the fluctuation and low-frequency noise (pulse noise) were observed in TMR heads. These were then related to the quality of the oxide layer in the TMR heads.

Thin film head for quasi-contact head/disk interface

A thin film head with a single, nearly square, flat ABS with adequate edge blend instead of a conventional two-rail taper-flat slider has been developed. The flying height of the head was adjusted to a value of between 0.03 mu m and 0.07 mu m at 11.3 m/sec of head/disk relative velocity by modifying the gross ABS area and a gram load to be applied. Read/write performance of the head was measured reliably on sputtered gamma -Fe/sub 2/O/sub 3/ disk with glass substrate. Significant improvement of electrical performance was attained primarily due to the extremely low flying height of the head. The head and the disk combination showed sufficient durability against 50000 cycles of in-contact start/stop operations. >