Jei-Wei Chang

Low Fringe-Field And Narrow-Track MR Heads

The ABS focused ion beam technique was utilized to pattern MR heads into different geometry at track edges to study side-writing performance. By spinstand testing, both written track width and erase distance were measured. An analytical model was developed to analyze the dependence of the side-writing on the etching step length. Effects of the etching width, which affects the total etching time, were also studied.

2 Gbits/in/sup 2/ Dual Stripe MR Heads

Dual-stripe MR heads with linear density capability of 200 KBPI and track density capability of 11000 TPI have been manufactured. The write head, with a 15 turn coil and a gap length of 0.3 /spl mu/m, is made of conventionally plated Permalloy for both the leading and trailing poles. The thickness and track width of the trailing pole are 3.5 and 2.1 /spl mu/m, respectively. The MR elements have a 1.4 /spl mu/m track width, 1.1 /spl mu/m stripe height and a 17.5 nm thickness. The shield-to-shield separation is 0.18 /spl mu/m. The two MR elements are mutually biased and patterned-exchange domain stabilized. Recording tests were performed on a thin-film disk with a coercivity of about 3000 Oe and an M/sub r/t of 0.75 memu/cm/sup 2/. The read-back amplitude is as large as 1.02 mV(p-p), and the 50% roll-off density is as high as 160 kfci. Error rate test with a PRML channel at a data rate of 105 Mbits/s showed that a low on track error rate of 10/sup -10/ and an off-track capability of more than 15% of the track pitch could be easily achieved at a linear density of 200 KBPI and a track density of 11000 TPI.

5 Gb/in/sup 2/ recording with dual stripe AMR heads and low noise thin film disks

We have demonstrated magnetic recording at an areal density of 5 Gb/in/sup 2/ using dual stripe magnetoresistive heads (DSMR) on low noise and low-glide height quaternary CoCrTa-based alloy thin film disks. The data rate is 120 Mb/sec with a PR4 channel, and the on-track error rate achieved is around 10/sup -9/. The demonstration was accomplished in two cases using two different types of heads. In the first case, it was done with a DSMR head having shield-shield spacing of 0.165 /spl mu/m and 1 /spl mu/m stripe height flying at 25 nm, resulting in a linear density of 321.7 KBPI, and a track density of 15.6 KTPI. The second case was performed with DSMR heads having shield-shield spacing of 0.18 /spl mu/m and 8 /spl mu/m stripe height flying at proximity height of 12 nm, achieving a 358.75 KBPI and 13.8 KTPI. This is the highest linear density published so far for either GMR or AMR heads. It is the direct consequence of high signal/noise of DSMR heads and proximity recording over low noise, low-glide-height media. To explore the large dynamic range of DSMR heads, this study was also done with a variety of low noise disks with Mrt ranging broadly from 0.45 to 1.0 memu/cm/sup 2/ and coercivity of 3000 Oe.