Triple-layer perpendicular recording media for high SN ratio and signal stability

Ando, Toshio; Nishihara, Toshikazu

doi:10.1109/20.617818

Cited by 42 publications

(17 citation statements)

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“…1,2 The technological relevance of these materials ranges from applications as permanent magnets, 3 as giant magnetoresistance ͑GMR͒ spin devices, 4 to usage for advanced recording media. 5 The system studied in this article is a model of a ͓110͔ ͓50 Å DyFe 2 / 200 Å YFe 2 ͔ ϫ 27 Laves phase superlattice. Macroscopic magnetization measurements as well as compound-resolved x-ray magnetic circular dichroism ͑XMCD͒ analysis 6,7 reveal an unexpected switching behavior with three irreversible switchings for high temperature ͑HTs͒ and a typical exchange spring magnetization reversal for low temperature ͑LTs͒.…”

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confidence: 99%

Micromagnetic simulation of the magnetic exchange spring system DyFe2∕YFe2

Zimmermann

Bordignon

Boardman

et al. 2006

Journal of Applied Physics

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Magnetic measurements of ͓110͔ ͓50 Å DyFe 2 / 200 Å YFe 2 ͔ reveal a rich switching behavior: the formation of exchange springs in this system of alternating hard and soft layers can be observed for low temperatures ͑LTs͒. For high temperatures ͑HTs͒, the appearance of the hysteresis loop changes significantly, implying a more complicated reversal process. In this article, we reproduce hysteresis loops for net and compound-specific magnetizations by means of micromagnetic simulations and assess the quality by a direct comparison to recent x-ray magnetic circular dichroism measurements. The HT switching characteristics, showing a magnetization reversal of the hard magnetic layer before the soft magnetic layer, are investigated and understood on the basis of detailed magnetic configuration plots. The crossover of LT to HT switching patterns is explained by energy considerations, and the dependence on different parameters is outlined.

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confidence: 99%

Micromagnetic simulation of the magnetic exchange spring system DyFe2∕YFe2

Zimmermann

Bordignon

Boardman

et al. 2006

Journal of Applied Physics

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“…The saturation plots of Head A and Head B are shown in Fig.4. The low noise double layered medium with the recording layer having Bs of 0.5T, thickness of 50nm, and coercive force of 192kA1m(24000e), was used [6]. Table 1 shows experimental parameters.…”

Section: B Write Performancesmentioning

confidence: 99%

Write Characteristics of Simple Structured Single Pole Head

et al. 1997

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Abstract----The write head design for a merged MR head needs to be optimized to obtain a good wrIte performance for a perpendicular magnetic recording application. We fabricated a write-only single pole head with the simplified structure which consists of a main pole and a thin film coil without a return yoke. The write performance of the single pole head with double-layered media was evaluated by using an MR read head. The O/W value obtained was less than -35dB, and the PWso value obtained from the differentiated curve of the readback waveform was 0.20 J1 m. The small PWsofrom the recorded bits attributes to the sharp magnetic transitions.Key words: perpendicular magnetic recording, single pole head, simplified structure, write head, MR head, I . INTRODUCTIONPerpendicular magnetic recording is expected to be an important technology for high recording density. The areal density of lOGbitslin 2 and beyond was obtained experimentally, using a sjngle-pole head and a double-layered perpendicular medium [1]. The combination of an MR head and a double-layered medium is also a promising technology for future high-density recording [2]. Muraoka et.at. pointed out the 50% linear density(D50) of the roll-off curve measured by the MR head increased by 70% associating with the differential equalizer [3].If an MR head is used as a read element, a write head becomes simplified structure which consists of a main pole and a thin film coil, without a return yoke. It is because the recording process of a perpendicular magnetic recording single pole head on a double-layered medium is carried out through a main pole, a recording layer and an under-layer of the medium.It is considered that write head design should be optimized to obtain a good write performance of the merged MR head for perpendicular magnetic recording. In this study, we developed a simple structured write-only single pole head without the return yoke on the basis of analytical results from a computer simulation. The structure and write characteristics of the write-only single pole head when read out by the MR head are discussed. IT . EXPERIMENTALThe write magnetic field amplitude ofthe simplified singlepole head without a return yoke(Head A) was calculated using a three-dimensional finite element method, and that of the conventional single pole head(Head B) [4] was also calculated for comparison.The head was fabricated by a thin film process with the help of an analytical simulation. Electrical performances of the head were measured by a GUZIK read/write analyzer (RWA1601), and an MRhead was used as a read head at the flying height of 40nm.In order to investigate the write performance of Head A, we measured saturation characteristics for this head, and also measured for Head B as a reference. The roll-off curves and isolated waveforms when read by the MR head were measured for the following three cases concerning media and write heads. Case A; a longitudinal medium and a ring head, Case B; a perpendicular medium and a ring head, and Case C; a perpendicular medium a...

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“…However, as the areal density increased beyond 10 Gb/in 2 , the signal decay problem associated with thermal instability with LMR [7][8][9] gradually narrowed the allowance in HDD product design. Triggered by a highdensity magnetic recording demonstration using PMR 10) and by the developments of PMR media technology which solved the engineering issues [11][12][13][14][15][16][17][18] , activities toward realization of HDD products based on PMR emerged drastically in the magnetic recording community from the year around 2000 and the first PMR-HDD product was shipped in 2005 with an areal density of 133 Gb/in 2 19, 20) . The areal density of PMR-HDD increased since then about 10 times and the technologies for achieving 5 -10 Tb/in 2 areal densities are investigated in the cutting edge research laboratories 21,22) .…”

Section: Introductionmentioning

confidence: 99%

“…The PMR media used in commercial HDDs employ the double magnetic layer structure consisting of a semi-hard magnetic recording layer stacked on a soft magnetic underlayer, which is the basic PMR structure proposed by Prof. Iwasaki 1) . Until late 1990's, the Co-alloy recording layer was deposited directly on a thick softmagnetic underlayer of crystalline Fe-Ni 94,95) , amorphous Co-Zr-Nb 11,96) , etc. However, a series of research has shown that the medium noise can be reduced by introducing a thin nonmagnetic layer between the soft magnetic underlayer and the semi-hard recording layer, where the nonmagnetic layer is now defined as an intermediate layer since the soft magnetic layer is called as "underlayer" in the double layer structure 97) .…”

Section: Introductionmentioning

confidence: 99%

Development of Media Nanostructure for Perpendicular Magnetic Recording

Futamoto

Ohtake

2017

J. Magn. Soc. Jpn.

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The review covers the research and development of perpendicular media nanostructure focusing on the recording layer. The recording layer material includes the Co-alloys with hcp structure, the magnetic multilayers, and the alloys with ordered structures that have high magneto-crystalline anisotropies (Ku). The technologies of underlayer or interlayer for aligning the easy magnetization axis of magnetic crystal grain perpendicular to the film plane are briefly reviewed including the high Ku magnetic materials for future recording media.Observations of compositional and magnetization structures in sub-µm scale have played important roles in improving the recording layer. Typical data on these characteristics are explained in relation to the media structure improvements. Considering that high Ku magnetic materials will be employed in future recording media, basic experimental results related in controlling the easy magnetization axis and in keeping the surface flatness of L10-ordered magnetic materials are explained. Future possibilities for increasing the areal density beyond 1 Tb/in 2 by improving the magnetic material and the nanostructure of recording layer are also discussed.

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Triple-layer perpendicular recording media for high SN ratio and signal stability

Cited by 42 publications

References 9 publications

Micromagnetic simulation of the magnetic exchange spring system DyFe2∕YFe2

Micromagnetic simulation of the magnetic exchange spring system DyFe2∕YFe2

Write Characteristics of Simple Structured Single Pole Head

Development of Media Nanostructure for Perpendicular Magnetic Recording

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