Pub Date : 2003-01-06DOI: 10.1109/NAPMRC.2003.1177044
V. Minuhin
This paper gives a theoretical discussion on the subject of correlation versus convolution in magnetic recording, and outlines various misconceptions which have arisen in the signal processing field. It details errors in the usage of convolution and how this technique does not apply to perpendicular magnetic recording.
{"title":"Superposition in magnetic readback","authors":"V. Minuhin","doi":"10.1109/NAPMRC.2003.1177044","DOIUrl":"https://doi.org/10.1109/NAPMRC.2003.1177044","url":null,"abstract":"This paper gives a theoretical discussion on the subject of correlation versus convolution in magnetic recording, and outlines various misconceptions which have arisen in the signal processing field. It details errors in the usage of convolution and how this technique does not apply to perpendicular magnetic recording.","PeriodicalId":111090,"journal":{"name":"Joint NAPMRC 2003. Digest of Technical Papers","volume":"2013 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121430587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-01-06DOI: 10.1109/NAPMRC.2003.1177037
M. Xiao, K. Takano, H. Rosen, S. Faruque
With decreasing trackwidth, track density increases while jitter goes up, limiting the linear density. Overall, we expect a gain in areal density with reducing bit aspect ratio (BAR). In order to create narrow trackwidths thereby achieve small BAR, we utilized the microtrack technique. This novel approach enabled us to produce narrow tracks with varying widths without using special heads. We measured the jitter of microtracks, verified jitter dependence on the effective reader width and established the areal density relationship with BAR.
{"title":"Studies of bit aspect ratio and areal density using microtracks","authors":"M. Xiao, K. Takano, H. Rosen, S. Faruque","doi":"10.1109/NAPMRC.2003.1177037","DOIUrl":"https://doi.org/10.1109/NAPMRC.2003.1177037","url":null,"abstract":"With decreasing trackwidth, track density increases while jitter goes up, limiting the linear density. Overall, we expect a gain in areal density with reducing bit aspect ratio (BAR). In order to create narrow trackwidths thereby achieve small BAR, we utilized the microtrack technique. This novel approach enabled us to produce narrow tracks with varying widths without using special heads. We measured the jitter of microtracks, verified jitter dependence on the effective reader width and established the areal density relationship with BAR.","PeriodicalId":111090,"journal":{"name":"Joint NAPMRC 2003. Digest of Technical Papers","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131097268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-01-06DOI: 10.1109/NAPMRC.2003.1177054
T. Suzuki, K. Ouchi
Perpendicular recording is fundamentally characterized by demagnetizing field free transitions. This principal feature is a great advantage not only for granular type media but also laterally exchange-coupled (LEC) film media with enhanced wall-pinning effects. Recently, it has been first reported that larger M/sub s/ and K/sub u/, high density pinning sites, and thinner recording layer of LEC film media are effective for coexistence of a larger hysteresis loop slope parameter, /spl alpha/, and a smaller domain size. Thus, higher recording and reproducing resolutions and lower media noise are expected to be realized by the media. Since an ordered Fe-Pt alloy of L1/sub 0/ phase satisfies the requirements for the LEC film media, we discuss the potential of thinner Fe-Pt film media for perpendicular magnetic recording.
{"title":"Possibilities of Fe-Pt media for ultra-high density perpendicular magnetic recording","authors":"T. Suzuki, K. Ouchi","doi":"10.1109/NAPMRC.2003.1177054","DOIUrl":"https://doi.org/10.1109/NAPMRC.2003.1177054","url":null,"abstract":"Perpendicular recording is fundamentally characterized by demagnetizing field free transitions. This principal feature is a great advantage not only for granular type media but also laterally exchange-coupled (LEC) film media with enhanced wall-pinning effects. Recently, it has been first reported that larger M/sub s/ and K/sub u/, high density pinning sites, and thinner recording layer of LEC film media are effective for coexistence of a larger hysteresis loop slope parameter, /spl alpha/, and a smaller domain size. Thus, higher recording and reproducing resolutions and lower media noise are expected to be realized by the media. Since an ordered Fe-Pt alloy of L1/sub 0/ phase satisfies the requirements for the LEC film media, we discuss the potential of thinner Fe-Pt film media for perpendicular magnetic recording.","PeriodicalId":111090,"journal":{"name":"Joint NAPMRC 2003. Digest of Technical Papers","volume":"144 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133139070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-01-06DOI: 10.1109/NAPMRC.2003.1177016
Wen Jiang, M. Williams, N. Smith, W. Weresin, K. Kuroki, Y. Ikeda, K. Takano, G. Khera, R. Wood
As areal densities increase and track-widths become narrower, adjacent-track interference (ATI) is becoming a major engineering concern in magnetic recording systems. In perpendicular recording, the nature of ATI is more complex due to the novel head designs and the soft underlayer. ATI arises when stray fields from the sides of a head cause erasure or create interference on an adjacent track. To uncover the sources of ATI in perpendicular systems, we developed a method using DC erase noise to identify the polarity as well as the extent and magnitude of the stray fields. This paper extends this earlier work to explain some of the puzzling phenomena that were observed and explores further the general ATI issues such as rate of signal decay with multiple writes and ultimately the impact on error-rate.
{"title":"Investigations on adjacent-track interference in perpendicular recording systems","authors":"Wen Jiang, M. Williams, N. Smith, W. Weresin, K. Kuroki, Y. Ikeda, K. Takano, G. Khera, R. Wood","doi":"10.1109/NAPMRC.2003.1177016","DOIUrl":"https://doi.org/10.1109/NAPMRC.2003.1177016","url":null,"abstract":"As areal densities increase and track-widths become narrower, adjacent-track interference (ATI) is becoming a major engineering concern in magnetic recording systems. In perpendicular recording, the nature of ATI is more complex due to the novel head designs and the soft underlayer. ATI arises when stray fields from the sides of a head cause erasure or create interference on an adjacent track. To uncover the sources of ATI in perpendicular systems, we developed a method using DC erase noise to identify the polarity as well as the extent and magnitude of the stray fields. This paper extends this earlier work to explain some of the puzzling phenomena that were observed and explores further the general ATI issues such as rate of signal decay with multiple writes and ultimately the impact on error-rate.","PeriodicalId":111090,"journal":{"name":"Joint NAPMRC 2003. Digest of Technical Papers","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115721560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-01-06DOI: 10.1109/NAPMRC.2003.1177048
S. Sankaranarayanan, E. Kurtas, B. Vasic
Cheng (Doctoral Dissertation, CIT, Pasadena, California, 1997) introduced a class of linear codes called low-density generator matrix (LDGM) codes and studied its performance on a memoryless additive white Gaussian noise (AWGN) channel. In this paper, we study its performance on perpendicular magnetic recording channels. The results shown in this paper indicate that the bit-error rate (BER) performance of some LDGM-codes is comparable to that of low-density parity check (LDPC) codes of the same rate.
{"title":"Performance of low-density generator matrix codes on perpendicular recording channels","authors":"S. Sankaranarayanan, E. Kurtas, B. Vasic","doi":"10.1109/NAPMRC.2003.1177048","DOIUrl":"https://doi.org/10.1109/NAPMRC.2003.1177048","url":null,"abstract":"Cheng (Doctoral Dissertation, CIT, Pasadena, California, 1997) introduced a class of linear codes called low-density generator matrix (LDGM) codes and studied its performance on a memoryless additive white Gaussian noise (AWGN) channel. In this paper, we study its performance on perpendicular magnetic recording channels. The results shown in this paper indicate that the bit-error rate (BER) performance of some LDGM-codes is comparable to that of low-density parity check (LDPC) codes of the same rate.","PeriodicalId":111090,"journal":{"name":"Joint NAPMRC 2003. Digest of Technical Papers","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131263485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-01-06DOI: 10.1109/NAPMRC.2003.1177021
Y. Ikeda, N. Supper, K. Takano, H. Do
Perpendicular recording is the most promising candidate to achieve areal densities exceeding 1 Tbit/in/sup 2/. To achieve this goal, small grains with high uniaxial anisotropy and good magnetic isolation are required for the media. However, the optimum exchange coupling is also necessary to reduce DC-erase noise caused by the reversed grains due to the high demagnetization field. The high nucleation field H/sub n/, and the low noise of the CoPtCrO perpendicular medium are attractive features. In this paper, the medium noise and exchange coupling correlation has been investigated by changing the oxygen ratio in the sputter gas.
{"title":"Inter-granular exchange coupling control by oxygen ratio in CoPtCrO perpendicular media","authors":"Y. Ikeda, N. Supper, K. Takano, H. Do","doi":"10.1109/NAPMRC.2003.1177021","DOIUrl":"https://doi.org/10.1109/NAPMRC.2003.1177021","url":null,"abstract":"Perpendicular recording is the most promising candidate to achieve areal densities exceeding 1 Tbit/in/sup 2/. To achieve this goal, small grains with high uniaxial anisotropy and good magnetic isolation are required for the media. However, the optimum exchange coupling is also necessary to reduce DC-erase noise caused by the reversed grains due to the high demagnetization field. The high nucleation field H/sub n/, and the low noise of the CoPtCrO perpendicular medium are attractive features. In this paper, the medium noise and exchange coupling correlation has been investigated by changing the oxygen ratio in the sputter gas.","PeriodicalId":111090,"journal":{"name":"Joint NAPMRC 2003. Digest of Technical Papers","volume":" 15","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132074326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-01-06DOI: 10.1109/NAPMRC.2003.1177012
H. Sawaguchi, Y. Nishida, T. Nakagawa, H. Takano, H. Aoi
Non-stationary media noise is one of the major disturbances that occur in higher density perpendicular magnetic recording channels. The strongly signal-dependent and correlated statistical nature of this noise means that it significantly worsens error-rates of traditional partial-response maximum likelihood (PRML) data-detection. As densities of recording become increasingly high, thermal stability issues place serious restrictions on the use of smaller grained recording media to reduce the media noise. To mitigate requirements for the noise reduction, we have introduced a sub-optimal ML detection scheme for media-noise-dominant channels. This scheme is based on the estimation of signal-dependent correlation-sensitive (SDCS) metric for soft-output postprocessing detection. By focusing on correcting only a few most-likely error-events in PRML detection, this media-noise soft-output detection scheme provides a good tradeoff between detection performance and computational complexity.
{"title":"Signal processing and coding techniques for perpendicular recording","authors":"H. Sawaguchi, Y. Nishida, T. Nakagawa, H. Takano, H. Aoi","doi":"10.1109/NAPMRC.2003.1177012","DOIUrl":"https://doi.org/10.1109/NAPMRC.2003.1177012","url":null,"abstract":"Non-stationary media noise is one of the major disturbances that occur in higher density perpendicular magnetic recording channels. The strongly signal-dependent and correlated statistical nature of this noise means that it significantly worsens error-rates of traditional partial-response maximum likelihood (PRML) data-detection. As densities of recording become increasingly high, thermal stability issues place serious restrictions on the use of smaller grained recording media to reduce the media noise. To mitigate requirements for the noise reduction, we have introduced a sub-optimal ML detection scheme for media-noise-dominant channels. This scheme is based on the estimation of signal-dependent correlation-sensitive (SDCS) metric for soft-output postprocessing detection. By focusing on correcting only a few most-likely error-events in PRML detection, this media-noise soft-output detection scheme provides a good tradeoff between detection performance and computational complexity.","PeriodicalId":111090,"journal":{"name":"Joint NAPMRC 2003. Digest of Technical Papers","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132486345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-01-06DOI: 10.1109/NAPMRC.2003.1177053
K. Takano, M. Xiao, H. Do, S. Faruque, E. Fullerton
The authors discuss work on the magnetic characterization and recording performance of Co/Pd multilayers deposited on various soft underlayer (SUL) and exchange break layer (EBL) structures. The dependence of various recording parametrics were measured as a function of the SUL and EBL thickness and the dimensions of the pole head were investigated. Significant issues behind the transition from dual layer to single layer perpendicular recording are also discussed.
{"title":"Multilayer media:role of the exchange break layer and soft underlayer thicknesses","authors":"K. Takano, M. Xiao, H. Do, S. Faruque, E. Fullerton","doi":"10.1109/NAPMRC.2003.1177053","DOIUrl":"https://doi.org/10.1109/NAPMRC.2003.1177053","url":null,"abstract":"The authors discuss work on the magnetic characterization and recording performance of Co/Pd multilayers deposited on various soft underlayer (SUL) and exchange break layer (EBL) structures. The dependence of various recording parametrics were measured as a function of the SUL and EBL thickness and the dimensions of the pole head were investigated. Significant issues behind the transition from dual layer to single layer perpendicular recording are also discussed.","PeriodicalId":111090,"journal":{"name":"Joint NAPMRC 2003. Digest of Technical Papers","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117153886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-01-06DOI: 10.1109/NAPMRC.2003.1177039
T. Shimatsu, T. Oikawa, Y. Inaba, H. Muraoka, Y. Nakamura
Magnetic cluster size of perpendicular recording media, which is a dominant factor for media noise was discussed relating to activation volume, the slope of magnetization curves, and remanence coercivity.
{"title":"Magnetic cluster size and magnetization curves in perpendicular recording media","authors":"T. Shimatsu, T. Oikawa, Y. Inaba, H. Muraoka, Y. Nakamura","doi":"10.1109/NAPMRC.2003.1177039","DOIUrl":"https://doi.org/10.1109/NAPMRC.2003.1177039","url":null,"abstract":"Magnetic cluster size of perpendicular recording media, which is a dominant factor for media noise was discussed relating to activation volume, the slope of magnetization curves, and remanence coercivity.","PeriodicalId":111090,"journal":{"name":"Joint NAPMRC 2003. Digest of Technical Papers","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130776355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-01-06DOI: 10.1109/NAPMRC.2003.1177072
M. Kryder
This paper gives a general overview of magnetic storage technology future trends. Areas covered include: perpendicular recording; magnetic head design; heat assisted magnetic recording (HAMR); media anisotropy; magnetic material isolated island patterned media; magnetic nanoparticle self-ordered arrays; and head-disk interface spacing.
{"title":"Future trends in magnetic storage technology","authors":"M. Kryder","doi":"10.1109/NAPMRC.2003.1177072","DOIUrl":"https://doi.org/10.1109/NAPMRC.2003.1177072","url":null,"abstract":"This paper gives a general overview of magnetic storage technology future trends. Areas covered include: perpendicular recording; magnetic head design; heat assisted magnetic recording (HAMR); media anisotropy; magnetic material isolated island patterned media; magnetic nanoparticle self-ordered arrays; and head-disk interface spacing.","PeriodicalId":111090,"journal":{"name":"Joint NAPMRC 2003. Digest of Technical Papers","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130824261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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