T. Toyooka

High-density recording characterization using a merged MR head and a dual-layer perpendicular disk

The combination of a merged MR head and a dual-layer perpendicular disk is a promising technology for future high-density recording. High-density recording using this combination was characterized to obtain a D/sub 50/ of 98 kFCI for read operations, a D/sub 50/ of 80 kFCI for write operations, and an overwrite of 50 dB, and the results were compared with those for longitudinal recording. Higher-density recording is expected to be achieved by optimizing the shield gap length in the read element, the pole thickness in the write element, and the Ms value of a disk.

Noise and /spl Delta/M/spl perp/ analysis of a Cr-rich Co-Cr perpendicular medium for an MR head

The medium noise in a Cr-rich Co-Cr alloy perpendicular medium was investigated by using an MR head designed for longitudinal recording. Medium with a Cr content of 28 at.% showed a high crystalline orientation and a low write-demagnetization effect. The signal-to-noise ratio (S/N) of the medium was higher than that of conventional Co-Cr perpendicular media for inductive heads. The advantages of the medium derive from the large inter-particle perpendicular magnetic interaction (/spl Delta/M/spl perp/) of media, which increased linearly with the Cr content, reaching a maximum value at 28 at.%. This strong interaction in the medium results in a high S/N for a recording system using a single-layer perpendicular medium and an MR head.

Characteristics of high-density recording using a single-layer perpendicular medium and a merged MR head

The combination of a merged MR head and a single-layer perpendicular medium is a promising technology for high-density recording. This paper describes a system that provides high-linear-density recording (over 150 kFCI) without requiring a contact recording method. Both-the large magnetic anisotropy and the large crystalline orientation of a Cr-rich Co/sub 72/Cr/sub 28/ medium hold out the promise of higher linear density. The large output signal also shows the possibility of increasing the track density. The baseline shift for narrow track widths is an issue that must be solved by equalization before this system can be used to realize future hard disk drive products.

Ti underlayer effect on the recording characteristics of Co–Cr perpendicular media with weak and strong interparticle interactions

We analyzed the effect of a Ti underlayer on the magnetic properties and read-write characteristics of perpendicular Co–Cr media, using a merged magnetoresistive head to investigate the latter. The output at 100 kfci for Co78Cr22 was decreased by using a Ti underlayer, whereas that for Co72Cr28 was increased. Such phenomena cannot be clearly explained only by the improvement in the crystalline orientation, the increase in the anisotropy field Hk⊥, and the reduction in the thickness of the initially grown layer. The maximum gradient in the curve showing the dependence of ΔM⊥ on the external field for the Co72Cr28 was about four times larger than that for the Co78Cr22. This result indicates that Co72Cr28 has strong interparticle interaction that aligns the magnetization direction of the particles coherently, and that the magnetization in the initial layer has a strong effect on the magnetization near the top surface through the exchange force. Consequently, the use of a Ti underlayer increases the reproduce...

High Signal-to-noise Ratio Of A Cr-Rich CoCrPt Perpendicular Medium With A Large Medium Thickness

A Cr-rich (Co/sub 72/Cr/sub 28/)/sub 94/Pt/sub 6/ perpendicular medium with a large thickness of 300 nm, integrated with an MR head designed for longitudinal recording, achieved a high signal-to-noise ratio of 37 dB at 100 kFCI and a D/sub 50/ of 150 kFCI. A high Pt content of 17-22 at.% is effective for increasing the Hk value and signal amplitude at 10 kFCI, and for decreasing the write demagnetization. However, it also decreases the S/N at 100 kFCI and the D/sub 50/. The signal amplitude rapidly increases with the Pt content from 0 to 6 at.%, and saturates at around 6 at.%. This contributes to the high S/N obtained at a Pt content of 6-11 at.%. Compared with a longitudinal medium optimized for the same MR head, the proposed medium has a 2 dB higher S/N at 100 kFCI, a 1.3 times larger D/sub 50/, and a 1.5 times larger signal amplitude at 10 kFCI. The thickness of the medium will contribute to the thermal stability of magnetic bits at future high recording density of 10 Gbits/in/sup 2/ and beyond.

Novel composite perpendicular recording medium with Co/sub 78/Cr/sub 22/ over Cr-rich Co/sub 72/Cr/sub 28/ for merged MR heads

We propose a new type of composite perpendicular medium consisting of a 50-nm-thick Co/sub 78/Cr/sub 22/ upper layer and a 50-nm-thick Cr-rich Co/sub 72/Cr/sub 28/ lower layer for magnetic recording systems using MR heads. The lower Cr-rich layer, with strong magnetic interaction in the perpendicular direction and good crystalline orientation, contributes to the high resolution and high signal-to-noise ratio (S/N). The upper layer, with large saturation magnetization (M/sub s/) and large anisotropy field (H/sub kl/), plays a major role in increasing the signal amplitude. Magnetic recording characterization using this medium and a merged MR head yielded a D/sub 50/ of 140 kFCI, an S/N of 33.4 dB, and a signal amplitude of 411 /spl mu/V/sub pp/ at 100 kFCI with a 62-nm magnetic spacing.

Characterization of a thick CoCr perpendicular medium for a merged MR head

Abstract We have been studying a single-layer CoCr perpendicular medium with a thickness of 100–700 nm, using a merged MR head designed for longitudinal recording. The Co 78 Cr 22 medium shows good linearity in its output dependence on the MR bias current. The output is 50% larger than that for a longitudinal medium. A maximum D 50 value of 100 kFCI was obtained for a medium with an optimum thickness of 300 nm. The medium noise increases with the medium thickness, whereas the output saturates at 300 nm. The thick medium has two demerits: large write demagnetization and a high level of medium noise. Increasing the Cr content of the CoCr medium from 22 to 28 at% significantly reduces these two problems. Cr-rich perpendicular media with thicknesses of over 100 nm are expected to replace longitudinal media in hard disk drives in the near future.