Role of thermal energy on the magnetic properties of laminated antiferromagnetically coupled recording media

Piramanayagam, S. N.; Hee, C. H.; Wang, J. P.

doi:10.1063/1.1399030

Cited by 23 publications

(9 citation statements)

References 19 publications

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“…In such a design, M r ␦ reduction is achieved by the partial cancellation of M r ␦ of one layer by that of the other. 75,77,80 Therefore, antiferromagnetic coupling can be observed even for smaller values of J ͑0.08 erg/ cm 2 ͒ than needed ͑about 1-2 erg/cm 2 ͒ in the absence of thermal energy. 78 In a simple energy model, to observe antiferromagnetic coupling at remanence, the antiferromagnetic coupling energy has to be greater than the anisotropy energy of the bottom layer grain ͑K u V͒.…”

Section: B Antiferromagnetically Coupled "Afc… Mediamentioning

confidence: 97%

“…33,[69][70][71][72][73][74][75][76][77] In conventional recording media, the M r ␦ reduction is achieved by a reduction in the thickness, which leads to a reduction in the K u V. This leads to superparamagnetic effects. 33,[69][70][71][72][73][74][75][76][77] In conventional recording media, the M r ␦ reduction is achieved by a reduction in the thickness, which leads to a reduction in the K u V. This leads to superparamagnetic effects.…”

Section: B Antiferromagnetically Coupled "Afc… Mediamentioning

confidence: 99%

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Perpendicular recording media for hard disk drives

Piramanayagam

2007

Journal of Applied Physics

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415

168

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Perpendicular recording technology has recently been introduced in hard disk drives for computer and consumer electronics applications. Although conceptualized in the late 1970s, making a product with perpendicular recording that has competing performance, reliability, and price advantage over the prevalent longitudinal recording technology has taken about three decades. One reason for the late entry of perpendicular recording is that the longitudinal recording technology was quite successful in overcoming many of its problems and in staying competitive. Other reasons are the risks, problems, and investment needed in making a successful transition to perpendicular recording technology. Iwasaki and co-workers came up with many inventions in the late 1970s, such as single-pole head, CoCr alloy media with a perpendicular anisotropy, and recording media with soft magnetic underlayers [S. Iwasaki and K. Takemura, IEEE Trans. Magn. 11, 1173 (1975); S. Iwasaki and Y. Nakamura, IEEE Trans. Magn. 14, 436 (1978); S. Iwasaki, Y. Nakamura, and K. Ouchi, IEEE Trans. Magn. 15, 1456 (1979)]. Nevertheless, the research on perpendicular recording media has been intense only in the past five years or so. The main reason for the current interest comes from the need to find an alternative technology to get away from the superparamagnetic limit faced by the longitudinal recording. Out of the several recording media materials investigated in the past, oxide based CoCrPt media have been considered a blessing. The media developed with CoCrPt-oxide or CoCrPt–SiO2 have shown much smaller grain sizes, lower noise, and larger thermal stability than the perpendicular recording media of the past, which is one of the reasons for the success of perpendicular recording. Moreover, oxide-based perpendicular media have also overtaken the current longitudinal recording media in terms of better recording performance. Several issues that were faced with the soft underlayers have also been solved by the use of antiferromagnetically coupled soft underlayers and soft underlayers that are exchange coupled with an antiferromagnetic layer. Significant improvements have also been made in the head design. All these factors now make perpendicular recording more competitive. It is expected that the current materials could theoretically support areal densities of up to 500–600Gbits∕in.2. In this paper, the technologies associated with perpendicular recording media are reviewed. A brief background of magnetic recording and the challenges faced by longitudinal recording technology are presented first, followed by the discussions on perpendicular recording media. Detailed discussions on various layers in the perpendicular recording media and the recent advances in these layers have been made. Some of the future technologies that might help the industry beyond the conventional perpendicular recording technology are discussed at the end of the paper.

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Section: B Antiferromagnetically Coupled "Afc… Mediamentioning

confidence: 97%

Section: B Antiferromagnetically Coupled "Afc… Mediamentioning

confidence: 99%

Perpendicular recording media for hard disk drives

Piramanayagam

2007

Journal of Applied Physics

Self Cite

415

168

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“…A kink in the hysteresis loops is a common feature of AFC samples and it occurs due to the magnetization reversal in one of the layers (the layer with the lowest coercivity) [20][21][22]. The position of the kink (whether it occurs in the first or second quadrant) is determined by the coercivity (Hc) and the exchange field (Hex), as reported earlier [20][21][22].…”

Section: A Afc Samplesmentioning

confidence: 56%

“…The position of the kink (whether it occurs in the first or second quadrant) is determined by the coercivity (Hc) and the exchange field (Hex), as reported earlier [20][21][22]. The inset in figure 2 shows the minor loops of the two samples.…”

Section: A Afc Samplesmentioning

confidence: 62%

Effect of Carbon Overcoat Implantation on the Magnetic and Structural Properties of Perpendicular Recording Media

et al. 2015

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Carbon overcoats play an important role in the corrosion protection of recording media used in hard disk drive technology. Filtered cathodic vacuum arc (FCVA) has been studied in the past as a potential technology for depositing media overcoat. In order to achieve desired property of FCVA carbon, it is essential to apply a suitable bias voltage, which results in an energetic carbon deposition on the magnetic layer of the recording media. In this paper, we focus our attention on the implantation effects of energetic carbon on the magnetic and structural properties of recording media of two types; AFC and a single layer, in order to gain a meaningful insight on the implantation and its effect. The studies reveal that the energetic deposition alters the anisotropy constant of the magnetic layer, resulting in a reduction in the coercivity and thermal stability factor.

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“…This can help to reduce M r ␦ more 7 and to also lower noise in the media. 8 The coercivity of the top layer, measured from the peak of the switching field distribution, also indicated that the films with CrZr underlayers showed slightly less coercivity, probably due to the smaller grain size.…”

Section: Resultsmentioning

confidence: 97%

Ultrasmall grain size control in longitudinal recording media for ultrahigh areal densities

Piramanayagam

Dai

et al. 2002

Journal of Applied Physics

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In this study, we propose a new “atomic wall” approach to underlayer design. In this design, a CrX underlayer is used where X and Cr are not miscible in the bulk phase, resulting in a reduced grain size. We have studied the addition of Zr to Cr layers and found that CrZr gives magnetic properties comparable to those of CrMo underlayers. In addition, a CrZr underlayer gives rise to a smaller grain size of 5.5 nm, in comparison to a grain size of 6.2 nm in the case of CrMo underlayers. To our knowledge, this is the smallest grain size reported for Co-alloy recording media. The recording measurements also show a higher signal to noise ratio for CrZr underlayers than for CrMo underlayers, suggesting that CrZr underlayers have potential for use in ultrahigh areal densities.

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Role of thermal energy on the magnetic properties of laminated antiferromagnetically coupled recording media

Cited by 23 publications

References 19 publications

Perpendicular recording media for hard disk drives

Perpendicular recording media for hard disk drives

Effect of Carbon Overcoat Implantation on the Magnetic and Structural Properties of Perpendicular Recording Media

Ultrasmall grain size control in longitudinal recording media for ultrahigh areal densities

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