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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.

Carbon overcoat has been used extensively on both disks and heads to enhance the tribological properties of head/disk interfaces. The electric properties, such as resistivity and breakdown voltage of the carbon overcoat are of great interest with the advent of magneto-resistance technology. The characterization and the underlying mechanisms of these electric properties will be extensively discussed. A highly reproducible computer-controlled voltage-current (V-I) setup, on carbon and ZrO/sub 2/ overcoats ranging from 100 to 250 /spl Aring/ in thickness, is used to measure resistance and breakdown voltage. An analytic model, based on the thermal and electrical properties of the carbon overcoat was used to interpret data. Basically, the model states that the increasing voltage causes thermal heating in the overcoat, thereby lowering its resistivity. Yet, when the applied field is sufficiently large, heating becomes excessive and thermal run-away occurs, resulting in the breakdown of the carbon. The model achieved good agreement with experimental results and its implication is discussed.

Recording results of write heads using sputtered laminated FeN/Al/sub 2/O/sub 3/ materials on thin film media with coercivity up to 3800 Oe are compared with those obtained using plated NiFe materials. The thickness of P2 (second pole) of FeN merged write heads is about 3.2 /spl mu/m, and those of plated NiFe heads, 3.5 and 6.3 /spl mu/m respectively. These heads have two write gap thickness, around 0.2 and 0.4 /spl mu/m. Various recording measurements show that these high magnetization FeN heads of 0.15 /spl mu/m gap write well on media of 3800 Oe, while the corresponding NiFe ones with a P2 of twice the thickness could not. For a wide 0.39 /spl mu/m gap, the FeN write heads still work well and the NiFe ones with twice the pole thickness, also did, but at reduced resolution, In short, write heads using a narrow gap and high magnetization materials such as FeN can write 3800 Oe coercivity media, which is capable of storing a bit density over 10 Gb/in/sup 2/. >

Hard bubble suppression with proton and neon implantation was achieved in one micron Eu .8 Tm 2.2 Ga .5 Fe 4.5 O 12 films. The dose and energy required in these one micron bubble films are similar to that required in five micron bubble films, despite the fact that the one micron films have larger uniaxial anisotropy to be overcome with the induced magnetostriction. In addition, controlled state generation (for bubble lattlce device applications) has been demonstrated in the proton implanted samples using two different techniques. The first technique, using a combination of an in-plane field and a critical velocity, is identical to what Hsu has reported with five micron bubbles, except that the in-plane field required in this case is 20 to 40% larger. The second technique, using DC and AC in-plane fields only without any field gradient, has also been shown. In the case of conversion from a bubble that propagates at an angle from the field gradient to one that propagates along the field gradient, a DC in-plane field of 300 Oe is needed. While in the reverse case, an AC in-plane field of 100 Oe or so is necessary.