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Perpendicular recording technology has become the main stream for 130 Gb/[in.sup.2] HDD products. In this paper, challenges in perpendicular write head are discussed. Design tradeoffs and concerns of narrow-track single-pole heads, trailing shield heads, floating TS heads, and wrapped-around-shield (WAS) heads are discussed. Experimental data show that WAS heads provide good narrow track and high linear density performance. An areal density of 343 Gb/[in.sup.2] has been achieved at a very aggressive magnetic spacing condition. Index Terms--Perpendicular magnetic recording, test and characterization, write heads.

In this work, we present an analysis of the recording performance and process tolerance of shielded dual-stripe MR heads. Using a micromagnetic model, we study isolated read-back pulses and the dependence of the peak asymmetry on both mismatch of the two MR stripes and off-track misalignment. Results show, as long as the two MR stripes are away from their saturation regions, the differential mode of the output does not have severe peak asymmetry caused by mismatch of the two MR stripes. The off-track performance study shows that peak asymmetry is also very small with up to 0.5 [[micro]meter] read-to-write misalignment. The linear resolution is found to be comparable to that of SAL-biased MR heads and insensitive to the spacer thickness between the two MR stripes.

Data erasure can arise when a hard disk drive is exposed to a large external magnetic field. This has been raised as a particular concern for drives employing perpendicular recording. Flux tends to concentrate between the head and the soft-underlayer of the disk, especially around the edges and corners of the head where the data erasure is often most pronounced. In this paper, we use 3-D finite-element modeling to investigate the effects of head geometry on the fields that cause data erasure. An in-plane external field causes concentration of magnetic flux at the edges of the return pole (RP) and the upper and lower shields of the reader (USL/LSL). We found increasing the length (downtrack) of these structures is effective in reducing the erasure fields. Aligning the edges of the RP, USL, and LSL is also shown to be a practicable and effective way to reducing the erasure fields. These erasure fields are aggravated when the write element is active. The fields that arise during writing must be taken into consideration when assessing data erasure. Index Terms--Corner erasure, external stray field, magnetic head, perpendicular magnetic recording, soft underlayer (SUL).

Magnetic lithography (qualitatively analogous to optical lithography) is a process that transfers information from a patterned magnetic mask (analog of optical photomask) to magnetic media (analog of photoresist). The mask consists of patterned soft magnetic material (FeNiCo, FeCo) deposited on a thin flexible substrate. A flexible magnetic mask is considered a key element for achieving intimate contact between mask and the media. When uniformly magnetized media is brought into contact with the flexible magnetic mask, an externally applied magnetic field selectively changes the magnetic orientation in the areas not contacted by the soft magnetic material. Samples of submicron patterned FeCo and FeNiCo flexible magnetic masks have been fabricated and magnetic transition patterns successfully transferred to hard disk CrCo-based magnetic media. The authors report on the magnetics of the pattern transfer, fabrication of magnetic masks on flexible plastic substrates, magnetic force microscopy images of the magnetic transition patterns, and disk spinstand tests. Index Terms--Flexible, magnetic lithography, magnetic mask, magnetic printing, magnetic recording, servo, servowriting.

It has been possible to determine high frequency high field permeability of patterned Ni80Fe20 and Ni45Fe55 thin films from lithographically defined toroids. The permeability was seen to rise as the excitation field increases because of increasing flux conduction from wall motion.

The suitability of a dual-stripe magneto-resistive (DSMR) head for near-contact recording is investigated. Common mode rejection of thermally induced pulses is derived by a model incorporating manufacturing tolerance, and verified experimentally. The rejection ratio is at least 20 dB. Experiments also indicated that a DSMR can survive near-contact conditions without premature degradation.

High frequency high field permeability of patterned Ni[sub 80]Fe[sub 20] and Ni[sub 45]Fe[sub 55] thin films was measured from lithographically defined toroids. Measurement frequency is up to 500 MHz and excitation field up to 5 Oe. Permeability rolloff is calculated from the inductance data. In this experiment, patterned widths range from 30 down to 0.5 μm. Our data suggest that the rotational permeability measured at low field excitation is sufficient to predict high frequency characteristics. The rotational permeability decreases with decreasing patterned width. The 0.5 μm wide permalloy device has μ of 80 and the Ni[sub 45]Fe[sub 55] 50. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Investigates the suitability of a dual-stripe magnetoresistive head for near-contact recording. Common mode injection of thermally induced pulses derived by a model incorporating manufacturing tolerance; Theoretical prediction.

The continuous and rapid increase of areal density in magnetic data storage systems required a continuous increase of the coercivity of the storage media. In order to be able to record on these everhigher-coercivity media, new soft magnetic materials for pole tips with increased magnetic moment had to be developed. Significant progress has been made during the last few years in electroplating alloys with high saturation magnetic flux density for use in writing heads. We review recent progress made in this area, with particular emphasis on the work done at IBM since the review paper on the subject was published in this journal in 1998 by Andricacos and Robertson. Reviewed here are the high-moment alloys of NiFe, particularly in the very high iron range [an extension of permalloy (Ni80Fe20) and Ni45Fe55]; very-high-cobalt CoFeCu alloys; ternary CoNiFe; and binary iron-rich CoFe alloys. With the latter binary alloy films, we have demonstrated that it is possible to reach by electroplating the saturation flux density limit of 2.4-2.5 T reported for cast alloys. Since the electroplating of good-magneticquality iron-rich CoFe alloys posed a considerable challenge, the behavior of the CoFe plating system was studied in detail, using in situ surface pH measurements and a rotating-cylinder Hull cell. [ABSTRACT FROM AUTHOR]