Noise characteristics of CoCrTa/NiFe perpendicular recording media

Sate, K.; Wakamatsu, H.; Shinohara, Asami

doi:10.1109/20.281284

Cited by 11 publications

(5 citation statements)

References 10 publications

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“…112 They have pointed out that the noise behavior depends on the permeability, which affects the domain structure. 112 They have pointed out that the noise behavior depends on the permeability, which affects the domain structure.…”

Section: Noise Of Sulmentioning

confidence: 99%

Perpendicular recording media for hard disk drives

Piramanayagam

2007

Journal of Applied Physics

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: Noise Of Sulmentioning

confidence: 99%

Perpendicular recording media for hard disk drives

Piramanayagam

2007

Journal of Applied Physics

415

168

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“…However, medium noise at low frequency increased (Fig. 4), which is from the underlayer [9,10], and as a result, the SNR dropped to about 6 dB. In the triple-layered medium (Medium C), which has the buffer layer between the storage layer and the soft magnetic underlayer, we supposed that the medium noise from the underlayer could be suppressed by increasing the spacing between the MR element of the head and the underlayer surface.…”

Section: Ill Resultsmentioning

confidence: 99%

Thermal Stability of Perpendicular and Longitudinal Recorded Information

et al. 1997

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Abstract---The decay times of information recorded on perpendicular and longitudinal recording media were measured with a commercial MR head. We confirmed that the recording information of both types of media decayed with time. Longitudinal recording media showed a large time decay at higher linear densities. caused by an increased demagnetizing field. On the other hand, perpendicular media showed a large time decay at low densities. We produced a triple-layered perpendicular medium (CoCr19PtTaNb /paramagnetic buffer layer/soft magnetic underlayer) to inhibit thermal fluctuations at low densities so as not to decrease the SNR.

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“…Many media samples created earlier by other workers [1][2][3][4][5] have been tested for various characteristics even though some results are not well understood. Readback simulation for double layer perpendicular recording media using Voronoi grain based media is one solution to help better understand perpendicular media.…”

Section: Introductionmentioning

confidence: 99%

Readback model for double layer perpendicular recording media

Senanan

Xue

Victora

2002

Journal of Applied Physics

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Articles you may be interested inRecording performance of CoCrPtO perpendicular media with single-domain hard magnet-biased soft magnetic underlayers J. Appl. Phys. 99, 08E702 (2006); 10.1063/1.2159409Reverse dc erase medium noise analysis on exchange-coupling effect in coupled granular/continuous perpendicular recording media A readback model is developed to study characteristics of perpendicular recording media with a soft underlayer. The model is applied to an experimental perpendicular recording media represented by Voronoi cells. The readback voltage from this model shows dependence both on the transition length and the fly-height separately. A roll-off curve produced from reading continuous, perfect arctangent transition media is compared to experimental results to obtain the transition length and the fly height. The calculated autocorrelation signal to noise ratio ͑SNR͒ from the model with Voronoi grain based media compared to those obtained from a particular example shows cluster forming with areas equal to about three times the grain size. This reduces the media SNR by about 4.7 dB. This readback model therefore allows SNR measurement to be converted to detailed understanding of the media structure.

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Noise characteristics of CoCrTa/NiFe perpendicular recording media

Cited by 11 publications

References 10 publications

Perpendicular recording media for hard disk drives

Perpendicular recording media for hard disk drives

Thermal Stability of Perpendicular and Longitudinal Recorded Information

Readback model for double layer perpendicular recording media

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