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Y Nakamura - One of the best experts on this subject based on the ideXlab platform.

  • effect of Thermal Agitation on the switching field distributions of coptcr sio2 perpendicular recording media
    Journal of Applied Physics, 2006
    Co-Authors: T Shimatsu, H Muraoka, T Kondo, K Mitsuzuka, S Watanabe, Y Nakamura
    Abstract:

    The effect of Thermal Agitations on the switching field distribution (SFD) of CoPtCr–SiO2 perpendicular media was investigated. Dc demagnetizing (DCD) magnetization curves and minor dc demagnetizing (M-DCD) magnetization curves were measured at applied field sweep rates of ∼10 and ∼108Oe∕s. We estimated the SFD from the difference between the DCD and M-DCD curves, and defined them as ΔHr∕Hr (at ∼10Oe∕s) and ΔHrP∕HrP (at ∼108Oe∕s). The values of ΔHrP∕HrP were found to be 60%–70% of ΔHr∕Hr. The difference between ΔHrP∕HrP and ΔHr∕Hr should be caused by Thermal Agitation of the magnetization. The influence of the distribution of the Thermal Agitation on SFD was calculated using the distribution of the grain volumes. It is concluded that the SFD measured at vibrating-sample magnetometer (VSM) time scales is significantly influenced by Thermal Agitation of the magnetization, and reduction of the grain size distribution is the most effective way to reduce the SFD at VSM time scales.

  • Effect of Thermal Agitation on the switching field distributions of CoPtCr–SiO2 perpendicular recording media
    Journal of Applied Physics, 2006
    Co-Authors: T Shimatsu, H Muraoka, T Kondo, K Mitsuzuka, S Watanabe, Y Nakamura
    Abstract:

    The effect of Thermal Agitations on the switching field distribution (SFD) of CoPtCr–SiO2 perpendicular media was investigated. Dc demagnetizing (DCD) magnetization curves and minor dc demagnetizing (M-DCD) magnetization curves were measured at applied field sweep rates of ∼10 and ∼108Oe∕s. We estimated the SFD from the difference between the DCD and M-DCD curves, and defined them as ΔHr∕Hr (at ∼10Oe∕s) and ΔHrP∕HrP (at ∼108Oe∕s). The values of ΔHrP∕HrP were found to be 60%–70% of ΔHr∕Hr. The difference between ΔHrP∕HrP and ΔHr∕Hr should be caused by Thermal Agitation of the magnetization. The influence of the distribution of the Thermal Agitation on SFD was calculated using the distribution of the grain volumes. It is concluded that the SFD measured at vibrating-sample magnetometer (VSM) time scales is significantly influenced by Thermal Agitation of the magnetization, and reduction of the grain size distribution is the most effective way to reduce the SFD at VSM time scales.

  • influence of Thermal Agitation on readback waveforms in perpendicular magnetic recording
    IEEE International Magnetics Conference, 2005
    Co-Authors: M Hashimoto, H Muraoka, T Suzuki, K Miura, Y Nakamura
    Abstract:

    In perpendicular magnetic recording, efforts to enhance magnetic isolation of grains to reduce transition jitter are in progress. However, the grain isolation tends to deteriorate Thermal stability. The quality of decayed signal of perpendicular recording media, therefore, becomes more important. In this paper, the influence of Thermal Agitation on signal quality is investigated for readback waveforms, pulse width, and jitter noise over elapsed time by time-domain analysis.

  • Thickness reduction in CoPtCr-SiO/sub 2/ perpendicular recording media to improve media performance
    IEEE Transactions on Magnetics, 2004
    Co-Authors: T Shimatsu, Isao Watanabe, H Muraoka, T. Oikawa, Y. Inaba, Hideo Sato, Y Nakamura
    Abstract:

    Magnetic properties and recording performance of thin CoPtCr-SiO/sub 2/ media were examined in relation to Thermal stability. Magnetic anisotropy K/sub u/ of {(Co/sub 90/Cr/sub 10/)/sub 80/Pt/sub 20/}/sub 89/-(SiO/sub 2/)/sub 11/ media maintains a constant value of around 5.5/spl times/10/sup 6/ erg/cm/sup 3/, even at film thickness of 4 nm. This K/sub u/ value corresponds to the anisotropy energy of the grains K/sub u//sup g/ calculated by taking account of the volume fraction of about 8/spl times/10/sup 6/ erg/cm/sup 3/, indicating a high potential to resist Thermal Agitation. The high K/sub u/ derives a high remanence coercivity H/sub r/ of /spl sim/4 kOe, even at film thickness of 8 nm, resulting in a loop squareness of nearly 1. The ratio of magnetic anisotropy energy to Thermal energy K/sub u/V/sub act//kT maintained a value of more than 70, even at this thickness. The media noise at low recording density increases with decreasing film thickness below 8 nm, probably due to the Thermal Agitation. The recording resolution D/sub 50/ showed a broad maximum of /spl sim/420 kFCI at around this thickness. The reduction in film thickness improves recording resolution; however, it is likely that the large Thermal Agitation in the thin-film region degrades the recording resolution, resulting in an optimum thickness to show the highest recording resolution.

  • Optimization of the SiO/sub 2/ content in CoPtCr-SiO/sub 2/ perpendicular recording media for high-density recording
    IEEE Transactions on Magnetics, 2004
    Co-Authors: Y. Inaba, T Shimatsu, H Muraoka, T. Oikawa, Hideo Sato, Y Nakamura
    Abstract:

    Optimization of the SiO/sub 2/ content for high-density recording was discussed for {(Co/sub 90/Cr/sub 10/)/sub 80/Pt/sub 20/}/sub 100-Z/-{SiO/sub 2/}/sub Z/ perpendicular recording media. The grain size D/sub grain/ decreases significantly from 8.8 to 5.4 nm as the SiO/sub 2/ content Z increases from 0 to 14.4; however, no significant difference in c-axis orientation was observed. Magnetocrystalline anisotropy of grains maintains a large value of nearly 8/spl times/10/sup 6/ erg/cm/sup 3/, even at 10 at % SiO/sub 2/ addition, indicating a high potential of perpendicular anisotropy K/sub u/ to resist Thermal Agitation of magnetization. The coercivity H/sub c/ increases significantly as the SiO/sub 2/ increases, which is coincident with the reduction of the slope of magnetization curve /spl alpha/=4/spl pi/(dM/dH) due to the enhancement of grain isolation. The H/sub c/ shows a maximum at around 11 at % SiO/sub 2/ (nearly 30 vol % SiO/sub 2/). A further increase of SiO/sub 2/ reduces the value of H/sub c/ significantly, although the /spl alpha/ maintains a constant value of nearly 2, due to Thermal Agitation of magnetization. The media noise reduces significantly as the SiO/sub 2/ increases; however, the addition of SiO/sub 2/ beyond about 13 at % leads to a slight increases in media noise probably due to a significant increase of Thermal Agitation. The recording resolution D/sub 50/ shows a broad maximum of /spl sim/420 kFCI at around 11 at % SiO/sub 2/, suggesting that the D/sub 50/ is related to the media noise performance. Experimental results indicate that there is a tradeoff to be made between the Thermal stability and media noise performance as a function of SiO/sub 2/ composition.

T Shimatsu - One of the best experts on this subject based on the ideXlab platform.

  • Pt Content Dependence of the Switching Field Distributions of CoPtCr-SiO $_{2}$ Perpendicular Media Characterized by Subtracting the Effect of Thermal Agitation
    IEEE Transactions on Magnetics, 2007
    Co-Authors: T Shimatsu, H Muraoka, T Kondo, K Mitsuzuka, S Watanabe, Y Nakamura
    Abstract:

    The switching field distributions (SFD) of CoPtCr-SiO2 perpendicular media as a function of Pt content were characterized by subtracting the effect of Thermal Agitation, and discussed in relation to the microstructure. DC demagnetizing (DCD) magnetization curves and minor dc demagnetizing (M-DCD) magnetization curves were measured at applied field sweep rates of ~10 Oe/s and ~108 Oe/s. We estimated the width of SFD, DeltaSFD, from the difference between the DCD and M-DCD curves, and defined them as DeltaHr/Hr (at ~ 10 Oe/s) and DeltaHr P/Hr P (at ~108 Oe/s). The values of DeltaSFD characterized by subtracting the effect of Thermal Agitation, DeltaH 0/H0, were nearly half those of DeltaHr /Hr for 10-nm-thick media. DeltaH0/H0 was about 0.10 at 10 at%Pt content, and increased as the Pt content increased, reaching 0.17 at 30 at%Pt content. The increase in DeltaH0/H0 was probably caused by an increase in the stacking fault density and the formation of fcc layers in the hcp CoPtCr lattice. A simple calculation based on the coherent switching of magnetization revealed that the c-axis distribution results in DeltaH 0/H0 of about 0.08, independent of Pt content. These results suggest that the DeltaSFD due to the grain-to-grain anisotropy field variation was small, only 0.02-0.03

  • Switching Field Distribution of CoPtCr-SiO $_2$ Perpendicular Recording Media Obtained by Subtracting Thermal Agitation of Magnetization
    INTERMAG 2006 - IEEE International Magnetics Conference, 2006
    Co-Authors: T Shimatsu, H Muraoka, T Kondo, K Mitsuzuka, S Watanabe, Y Nakamura
    Abstract:

    The effect of Thermal Agitations on the switching field distribution (SFD) of CoPtCr-SiO2 perpendicular media was investigated, and the "intrinsic" SFD caused by variations in the grain-to-grain switching field was determined. DC demagnetizing (DCD) magnetization curves and minor DCD (M-DCD) magnetization curves were measured at applied field-sweep rates of ~10 Oe/s and ~108 Oe/s. We estimated the SFD from the difference between the DCD and M-DCD curves, and defined them as DeltaHr/Hr (at ~10 Oe/s) and DeltaHr P/Hr P (at ~108 Oe/s). The values of DeltaHr/Hr were much larger than those of DeltaHr P/Hr P. Moreover, DeltaHr/Hr increased faster than DeltaHr P/Hr P as the thickness decreased, suggesting that the SFD measured at vibrating sample magnetometer (VSM) time scales is significantly influenced by Thermal Agitation. The intrinsic SFD estimated using a series of media with various film thicknesses was about 0.14, which was 55%-75% of DeltaHr/Hr for 8-16-nm-thick media. An analysis of the temperature dependence of DeltaHr/Hr supported this conclusion. It is concluded that the SFD measured at VSM time scales is significantly influenced by Thermal Agitation of the magnetization, and the intrinsic SFD is likely to be nearly half that measured at VSM time scales

  • effect of Thermal Agitation on the switching field distributions of coptcr sio2 perpendicular recording media
    Journal of Applied Physics, 2006
    Co-Authors: T Shimatsu, H Muraoka, T Kondo, K Mitsuzuka, S Watanabe, Y Nakamura
    Abstract:

    The effect of Thermal Agitations on the switching field distribution (SFD) of CoPtCr–SiO2 perpendicular media was investigated. Dc demagnetizing (DCD) magnetization curves and minor dc demagnetizing (M-DCD) magnetization curves were measured at applied field sweep rates of ∼10 and ∼108Oe∕s. We estimated the SFD from the difference between the DCD and M-DCD curves, and defined them as ΔHr∕Hr (at ∼10Oe∕s) and ΔHrP∕HrP (at ∼108Oe∕s). The values of ΔHrP∕HrP were found to be 60%–70% of ΔHr∕Hr. The difference between ΔHrP∕HrP and ΔHr∕Hr should be caused by Thermal Agitation of the magnetization. The influence of the distribution of the Thermal Agitation on SFD was calculated using the distribution of the grain volumes. It is concluded that the SFD measured at vibrating-sample magnetometer (VSM) time scales is significantly influenced by Thermal Agitation of the magnetization, and reduction of the grain size distribution is the most effective way to reduce the SFD at VSM time scales.

  • Effect of Thermal Agitation on the switching field distributions of CoPtCr–SiO2 perpendicular recording media
    Journal of Applied Physics, 2006
    Co-Authors: T Shimatsu, H Muraoka, T Kondo, K Mitsuzuka, S Watanabe, Y Nakamura
    Abstract:

    The effect of Thermal Agitations on the switching field distribution (SFD) of CoPtCr–SiO2 perpendicular media was investigated. Dc demagnetizing (DCD) magnetization curves and minor dc demagnetizing (M-DCD) magnetization curves were measured at applied field sweep rates of ∼10 and ∼108Oe∕s. We estimated the SFD from the difference between the DCD and M-DCD curves, and defined them as ΔHr∕Hr (at ∼10Oe∕s) and ΔHrP∕HrP (at ∼108Oe∕s). The values of ΔHrP∕HrP were found to be 60%–70% of ΔHr∕Hr. The difference between ΔHrP∕HrP and ΔHr∕Hr should be caused by Thermal Agitation of the magnetization. The influence of the distribution of the Thermal Agitation on SFD was calculated using the distribution of the grain volumes. It is concluded that the SFD measured at vibrating-sample magnetometer (VSM) time scales is significantly influenced by Thermal Agitation of the magnetization, and reduction of the grain size distribution is the most effective way to reduce the SFD at VSM time scales.

  • Thickness reduction in CoPtCr-SiO/sub 2/ perpendicular recording media to improve media performance
    IEEE Transactions on Magnetics, 2004
    Co-Authors: T Shimatsu, Isao Watanabe, H Muraoka, T. Oikawa, Y. Inaba, Hideo Sato, Y Nakamura
    Abstract:

    Magnetic properties and recording performance of thin CoPtCr-SiO/sub 2/ media were examined in relation to Thermal stability. Magnetic anisotropy K/sub u/ of {(Co/sub 90/Cr/sub 10/)/sub 80/Pt/sub 20/}/sub 89/-(SiO/sub 2/)/sub 11/ media maintains a constant value of around 5.5/spl times/10/sup 6/ erg/cm/sup 3/, even at film thickness of 4 nm. This K/sub u/ value corresponds to the anisotropy energy of the grains K/sub u//sup g/ calculated by taking account of the volume fraction of about 8/spl times/10/sup 6/ erg/cm/sup 3/, indicating a high potential to resist Thermal Agitation. The high K/sub u/ derives a high remanence coercivity H/sub r/ of /spl sim/4 kOe, even at film thickness of 8 nm, resulting in a loop squareness of nearly 1. The ratio of magnetic anisotropy energy to Thermal energy K/sub u/V/sub act//kT maintained a value of more than 70, even at this thickness. The media noise at low recording density increases with decreasing film thickness below 8 nm, probably due to the Thermal Agitation. The recording resolution D/sub 50/ showed a broad maximum of /spl sim/420 kFCI at around this thickness. The reduction in film thickness improves recording resolution; however, it is likely that the large Thermal Agitation in the thin-film region degrades the recording resolution, resulting in an optimum thickness to show the highest recording resolution.

T Shimatsu - One of the best experts on this subject based on the ideXlab platform.

  • influence of intergrain interactions and Thermal Agitation on microwave assisted magnetization switching behavior of granular magnetic film
    Applied Physics Express, 2017
    Co-Authors: S Okamoto, N Kikuchi, O Kitakami, T Shimatsu
    Abstract:

    Microwave-assisted magnetization switching (MAS) in a granular magnetic film is examined by computer simulation. Contrary to the macrospin calculation and the experiments on single magnetic dots reported so far, in which the switching field linearly decreases with increasing rf frequency and then sharply increases at the critical frequency, the granular film exhibits considerably broad MAS behavior against the rf frequency. This broad MAS behavior is mainly caused by the dispersion of magnetic properties and Thermal Agitation. On the other hand, intergrain dipolar and exchange interactions enhance the MAS effect in the granular film and suppress the MAS broadening.

  • pt content dependence of the switching field distributions of coptcr sio _ 2 perpendicular media characterized by subtracting the effect of Thermal Agitation
    IEEE Transactions on Magnetics, 2007
    Co-Authors: T Shimatsu, T Kondo, K Mitsuzuka, S Watanabe, H Muraoka, Y Nakamura
    Abstract:

    The switching field distributions (SFD) of CoPtCr-SiO2 perpendicular media as a function of Pt content were characterized by subtracting the effect of Thermal Agitation, and discussed in relation to the microstructure. DC demagnetizing (DCD) magnetization curves and minor dc demagnetizing (M-DCD) magnetization curves were measured at applied field sweep rates of ~10 Oe/s and ~108 Oe/s. We estimated the width of SFD, DeltaSFD, from the difference between the DCD and M-DCD curves, and defined them as DeltaHr/Hr (at ~ 10 Oe/s) and DeltaHr P/Hr P (at ~108 Oe/s). The values of DeltaSFD characterized by subtracting the effect of Thermal Agitation, DeltaH 0/H0, were nearly half those of DeltaHr /Hr for 10-nm-thick media. DeltaH0/H0 was about 0.10 at 10 at%Pt content, and increased as the Pt content increased, reaching 0.17 at 30 at%Pt content. The increase in DeltaH0/H0 was probably caused by an increase in the stacking fault density and the formation of fcc layers in the hcp CoPtCr lattice. A simple calculation based on the coherent switching of magnetization revealed that the c-axis distribution results in DeltaH 0/H0 of about 0.08, independent of Pt content. These results suggest that the DeltaSFD due to the grain-to-grain anisotropy field variation was small, only 0.02-0.03

  • switching field distribution of coptcr sio _2 perpendicular recording media obtained by subtracting Thermal Agitation of magnetization
    IEEE International Magnetics Conference, 2006
    Co-Authors: T Shimatsu, T Kondo, K Mitsuzuka, S Watanabe, H Muraoka, Y Nakamura
    Abstract:

    The effect of Thermal Agitations on the switching field distribution (SFD) of CoPtCr-SiO2 perpendicular media was investigated, and the "intrinsic" SFD caused by variations in the grain-to-grain switching field was determined. DC demagnetizing (DCD) magnetization curves and minor DCD (M-DCD) magnetization curves were measured at applied field-sweep rates of ~10 Oe/s and ~108 Oe/s. We estimated the SFD from the difference between the DCD and M-DCD curves, and defined them as DeltaHr/Hr (at ~10 Oe/s) and DeltaHr P/Hr P (at ~108 Oe/s). The values of DeltaHr/Hr were much larger than those of DeltaHr P/Hr P. Moreover, DeltaHr/Hr increased faster than DeltaHr P/Hr P as the thickness decreased, suggesting that the SFD measured at vibrating sample magnetometer (VSM) time scales is significantly influenced by Thermal Agitation. The intrinsic SFD estimated using a series of media with various film thicknesses was about 0.14, which was 55%-75% of DeltaHr/Hr for 8-16-nm-thick media. An analysis of the temperature dependence of DeltaHr/Hr supported this conclusion. It is concluded that the SFD measured at VSM time scales is significantly influenced by Thermal Agitation of the magnetization, and the intrinsic SFD is likely to be nearly half that measured at VSM time scales

  • switching field distribution of 40 gbit in 2 longitudinal media obtained by subtracting Thermal Agitation of magnetization
    Journal of Applied Physics, 2002
    Co-Authors: H Uwazumi, T Shimatsu, Y Kuboki
    Abstract:

    Switching field distributions (SFDs), are presented for longitudinal media of ∼40 Gbit/in.2 and the influence of Thermal Agitation of magnetization is discussed. Two remanence curves were measured at different sweep rates of applied field of ∼10 and ∼108 Oe/s, respectively, and SFD curves were obtained by differentiating the remanence curves. The SFD becomes significantly narrower at the higher field sweep rate. A SFD curve without the effect of Thermal Agitation was calculated using Sharrock’s equation. The full width at half maximum of the SFD curve at 10 Oe/s, ΔHr/Hr, is 0.45 for an isotropic medium, while that estimated without the Thermal Agitation effect ΔH0/H0 is 0.24, indicating that the SFD at the recording frequency is nearly half that measured at vibrating sample magnetometer (VSM) time scales. The ΔH0/H0 of the ∼40 Gbit/in.2 medium is much smaller than that of a 15 Gbit/in.2 medium used for comparison, although the ΔHr/Hr is ∼1.4 times larger than that of the 15 Gbit/in.2 medium due to Thermal...

  • Switching field distribution of 40 Gbit/in.2 longitudinal media obtained by subtracting Thermal Agitation of magnetization
    Journal of Applied Physics, 2002
    Co-Authors: H Uwazumi, T Shimatsu, Y Kuboki
    Abstract:

    Switching field distributions (SFDs), are presented for longitudinal media of ∼40 Gbit/in.2 and the influence of Thermal Agitation of magnetization is discussed. Two remanence curves were measured at different sweep rates of applied field of ∼10 and ∼108 Oe/s, respectively, and SFD curves were obtained by differentiating the remanence curves. The SFD becomes significantly narrower at the higher field sweep rate. A SFD curve without the effect of Thermal Agitation was calculated using Sharrock’s equation. The full width at half maximum of the SFD curve at 10 Oe/s, ΔHr/Hr, is 0.45 for an isotropic medium, while that estimated without the Thermal Agitation effect ΔH0/H0 is 0.24, indicating that the SFD at the recording frequency is nearly half that measured at vibrating sample magnetometer (VSM) time scales. The ΔH0/H0 of the ∼40 Gbit/in.2 medium is much smaller than that of a 15 Gbit/in.2 medium used for comparison, although the ΔHr/Hr is ∼1.4 times larger than that of the 15 Gbit/in.2 medium due to Thermal...

H Muraoka - One of the best experts on this subject based on the ideXlab platform.

  • Pt Content Dependence of the Switching Field Distributions of CoPtCr-SiO $_{2}$ Perpendicular Media Characterized by Subtracting the Effect of Thermal Agitation
    IEEE Transactions on Magnetics, 2007
    Co-Authors: T Shimatsu, H Muraoka, T Kondo, K Mitsuzuka, S Watanabe, Y Nakamura
    Abstract:

    The switching field distributions (SFD) of CoPtCr-SiO2 perpendicular media as a function of Pt content were characterized by subtracting the effect of Thermal Agitation, and discussed in relation to the microstructure. DC demagnetizing (DCD) magnetization curves and minor dc demagnetizing (M-DCD) magnetization curves were measured at applied field sweep rates of ~10 Oe/s and ~108 Oe/s. We estimated the width of SFD, DeltaSFD, from the difference between the DCD and M-DCD curves, and defined them as DeltaHr/Hr (at ~ 10 Oe/s) and DeltaHr P/Hr P (at ~108 Oe/s). The values of DeltaSFD characterized by subtracting the effect of Thermal Agitation, DeltaH 0/H0, were nearly half those of DeltaHr /Hr for 10-nm-thick media. DeltaH0/H0 was about 0.10 at 10 at%Pt content, and increased as the Pt content increased, reaching 0.17 at 30 at%Pt content. The increase in DeltaH0/H0 was probably caused by an increase in the stacking fault density and the formation of fcc layers in the hcp CoPtCr lattice. A simple calculation based on the coherent switching of magnetization revealed that the c-axis distribution results in DeltaH 0/H0 of about 0.08, independent of Pt content. These results suggest that the DeltaSFD due to the grain-to-grain anisotropy field variation was small, only 0.02-0.03

  • Switching Field Distribution of CoPtCr-SiO $_2$ Perpendicular Recording Media Obtained by Subtracting Thermal Agitation of Magnetization
    INTERMAG 2006 - IEEE International Magnetics Conference, 2006
    Co-Authors: T Shimatsu, H Muraoka, T Kondo, K Mitsuzuka, S Watanabe, Y Nakamura
    Abstract:

    The effect of Thermal Agitations on the switching field distribution (SFD) of CoPtCr-SiO2 perpendicular media was investigated, and the "intrinsic" SFD caused by variations in the grain-to-grain switching field was determined. DC demagnetizing (DCD) magnetization curves and minor DCD (M-DCD) magnetization curves were measured at applied field-sweep rates of ~10 Oe/s and ~108 Oe/s. We estimated the SFD from the difference between the DCD and M-DCD curves, and defined them as DeltaHr/Hr (at ~10 Oe/s) and DeltaHr P/Hr P (at ~108 Oe/s). The values of DeltaHr/Hr were much larger than those of DeltaHr P/Hr P. Moreover, DeltaHr/Hr increased faster than DeltaHr P/Hr P as the thickness decreased, suggesting that the SFD measured at vibrating sample magnetometer (VSM) time scales is significantly influenced by Thermal Agitation. The intrinsic SFD estimated using a series of media with various film thicknesses was about 0.14, which was 55%-75% of DeltaHr/Hr for 8-16-nm-thick media. An analysis of the temperature dependence of DeltaHr/Hr supported this conclusion. It is concluded that the SFD measured at VSM time scales is significantly influenced by Thermal Agitation of the magnetization, and the intrinsic SFD is likely to be nearly half that measured at VSM time scales

  • effect of Thermal Agitation on the switching field distributions of coptcr sio2 perpendicular recording media
    Journal of Applied Physics, 2006
    Co-Authors: T Shimatsu, H Muraoka, T Kondo, K Mitsuzuka, S Watanabe, Y Nakamura
    Abstract:

    The effect of Thermal Agitations on the switching field distribution (SFD) of CoPtCr–SiO2 perpendicular media was investigated. Dc demagnetizing (DCD) magnetization curves and minor dc demagnetizing (M-DCD) magnetization curves were measured at applied field sweep rates of ∼10 and ∼108Oe∕s. We estimated the SFD from the difference between the DCD and M-DCD curves, and defined them as ΔHr∕Hr (at ∼10Oe∕s) and ΔHrP∕HrP (at ∼108Oe∕s). The values of ΔHrP∕HrP were found to be 60%–70% of ΔHr∕Hr. The difference between ΔHrP∕HrP and ΔHr∕Hr should be caused by Thermal Agitation of the magnetization. The influence of the distribution of the Thermal Agitation on SFD was calculated using the distribution of the grain volumes. It is concluded that the SFD measured at vibrating-sample magnetometer (VSM) time scales is significantly influenced by Thermal Agitation of the magnetization, and reduction of the grain size distribution is the most effective way to reduce the SFD at VSM time scales.

  • Effect of Thermal Agitation on the switching field distributions of CoPtCr–SiO2 perpendicular recording media
    Journal of Applied Physics, 2006
    Co-Authors: T Shimatsu, H Muraoka, T Kondo, K Mitsuzuka, S Watanabe, Y Nakamura
    Abstract:

    The effect of Thermal Agitations on the switching field distribution (SFD) of CoPtCr–SiO2 perpendicular media was investigated. Dc demagnetizing (DCD) magnetization curves and minor dc demagnetizing (M-DCD) magnetization curves were measured at applied field sweep rates of ∼10 and ∼108Oe∕s. We estimated the SFD from the difference between the DCD and M-DCD curves, and defined them as ΔHr∕Hr (at ∼10Oe∕s) and ΔHrP∕HrP (at ∼108Oe∕s). The values of ΔHrP∕HrP were found to be 60%–70% of ΔHr∕Hr. The difference between ΔHrP∕HrP and ΔHr∕Hr should be caused by Thermal Agitation of the magnetization. The influence of the distribution of the Thermal Agitation on SFD was calculated using the distribution of the grain volumes. It is concluded that the SFD measured at vibrating-sample magnetometer (VSM) time scales is significantly influenced by Thermal Agitation of the magnetization, and reduction of the grain size distribution is the most effective way to reduce the SFD at VSM time scales.

  • influence of Thermal Agitation on readback waveforms in perpendicular magnetic recording
    IEEE International Magnetics Conference, 2005
    Co-Authors: M Hashimoto, H Muraoka, T Suzuki, K Miura, Y Nakamura
    Abstract:

    In perpendicular magnetic recording, efforts to enhance magnetic isolation of grains to reduce transition jitter are in progress. However, the grain isolation tends to deteriorate Thermal stability. The quality of decayed signal of perpendicular recording media, therefore, becomes more important. In this paper, the influence of Thermal Agitation on signal quality is investigated for readback waveforms, pulse width, and jitter noise over elapsed time by time-domain analysis.

T Kondo - One of the best experts on this subject based on the ideXlab platform.

  • pt content dependence of the switching field distributions of coptcr sio _ 2 perpendicular media characterized by subtracting the effect of Thermal Agitation
    IEEE Transactions on Magnetics, 2007
    Co-Authors: T Shimatsu, T Kondo, K Mitsuzuka, S Watanabe, H Muraoka, Y Nakamura
    Abstract:

    The switching field distributions (SFD) of CoPtCr-SiO2 perpendicular media as a function of Pt content were characterized by subtracting the effect of Thermal Agitation, and discussed in relation to the microstructure. DC demagnetizing (DCD) magnetization curves and minor dc demagnetizing (M-DCD) magnetization curves were measured at applied field sweep rates of ~10 Oe/s and ~108 Oe/s. We estimated the width of SFD, DeltaSFD, from the difference between the DCD and M-DCD curves, and defined them as DeltaHr/Hr (at ~ 10 Oe/s) and DeltaHr P/Hr P (at ~108 Oe/s). The values of DeltaSFD characterized by subtracting the effect of Thermal Agitation, DeltaH 0/H0, were nearly half those of DeltaHr /Hr for 10-nm-thick media. DeltaH0/H0 was about 0.10 at 10 at%Pt content, and increased as the Pt content increased, reaching 0.17 at 30 at%Pt content. The increase in DeltaH0/H0 was probably caused by an increase in the stacking fault density and the formation of fcc layers in the hcp CoPtCr lattice. A simple calculation based on the coherent switching of magnetization revealed that the c-axis distribution results in DeltaH 0/H0 of about 0.08, independent of Pt content. These results suggest that the DeltaSFD due to the grain-to-grain anisotropy field variation was small, only 0.02-0.03

  • Pt Content Dependence of the Switching Field Distributions of CoPtCr-SiO $_{2}$ Perpendicular Media Characterized by Subtracting the Effect of Thermal Agitation
    IEEE Transactions on Magnetics, 2007
    Co-Authors: T Shimatsu, H Muraoka, T Kondo, K Mitsuzuka, S Watanabe, Y Nakamura
    Abstract:

    The switching field distributions (SFD) of CoPtCr-SiO2 perpendicular media as a function of Pt content were characterized by subtracting the effect of Thermal Agitation, and discussed in relation to the microstructure. DC demagnetizing (DCD) magnetization curves and minor dc demagnetizing (M-DCD) magnetization curves were measured at applied field sweep rates of ~10 Oe/s and ~108 Oe/s. We estimated the width of SFD, DeltaSFD, from the difference between the DCD and M-DCD curves, and defined them as DeltaHr/Hr (at ~ 10 Oe/s) and DeltaHr P/Hr P (at ~108 Oe/s). The values of DeltaSFD characterized by subtracting the effect of Thermal Agitation, DeltaH 0/H0, were nearly half those of DeltaHr /Hr for 10-nm-thick media. DeltaH0/H0 was about 0.10 at 10 at%Pt content, and increased as the Pt content increased, reaching 0.17 at 30 at%Pt content. The increase in DeltaH0/H0 was probably caused by an increase in the stacking fault density and the formation of fcc layers in the hcp CoPtCr lattice. A simple calculation based on the coherent switching of magnetization revealed that the c-axis distribution results in DeltaH 0/H0 of about 0.08, independent of Pt content. These results suggest that the DeltaSFD due to the grain-to-grain anisotropy field variation was small, only 0.02-0.03

  • switching field distribution of coptcr sio _2 perpendicular recording media obtained by subtracting Thermal Agitation of magnetization
    IEEE International Magnetics Conference, 2006
    Co-Authors: T Shimatsu, T Kondo, K Mitsuzuka, S Watanabe, H Muraoka, Y Nakamura
    Abstract:

    The effect of Thermal Agitations on the switching field distribution (SFD) of CoPtCr-SiO2 perpendicular media was investigated, and the "intrinsic" SFD caused by variations in the grain-to-grain switching field was determined. DC demagnetizing (DCD) magnetization curves and minor DCD (M-DCD) magnetization curves were measured at applied field-sweep rates of ~10 Oe/s and ~108 Oe/s. We estimated the SFD from the difference between the DCD and M-DCD curves, and defined them as DeltaHr/Hr (at ~10 Oe/s) and DeltaHr P/Hr P (at ~108 Oe/s). The values of DeltaHr/Hr were much larger than those of DeltaHr P/Hr P. Moreover, DeltaHr/Hr increased faster than DeltaHr P/Hr P as the thickness decreased, suggesting that the SFD measured at vibrating sample magnetometer (VSM) time scales is significantly influenced by Thermal Agitation. The intrinsic SFD estimated using a series of media with various film thicknesses was about 0.14, which was 55%-75% of DeltaHr/Hr for 8-16-nm-thick media. An analysis of the temperature dependence of DeltaHr/Hr supported this conclusion. It is concluded that the SFD measured at VSM time scales is significantly influenced by Thermal Agitation of the magnetization, and the intrinsic SFD is likely to be nearly half that measured at VSM time scales

  • Switching Field Distribution of CoPtCr-SiO $_2$ Perpendicular Recording Media Obtained by Subtracting Thermal Agitation of Magnetization
    INTERMAG 2006 - IEEE International Magnetics Conference, 2006
    Co-Authors: T Shimatsu, H Muraoka, T Kondo, K Mitsuzuka, S Watanabe, Y Nakamura
    Abstract:

    The effect of Thermal Agitations on the switching field distribution (SFD) of CoPtCr-SiO2 perpendicular media was investigated, and the "intrinsic" SFD caused by variations in the grain-to-grain switching field was determined. DC demagnetizing (DCD) magnetization curves and minor DCD (M-DCD) magnetization curves were measured at applied field-sweep rates of ~10 Oe/s and ~108 Oe/s. We estimated the SFD from the difference between the DCD and M-DCD curves, and defined them as DeltaHr/Hr (at ~10 Oe/s) and DeltaHr P/Hr P (at ~108 Oe/s). The values of DeltaHr/Hr were much larger than those of DeltaHr P/Hr P. Moreover, DeltaHr/Hr increased faster than DeltaHr P/Hr P as the thickness decreased, suggesting that the SFD measured at vibrating sample magnetometer (VSM) time scales is significantly influenced by Thermal Agitation. The intrinsic SFD estimated using a series of media with various film thicknesses was about 0.14, which was 55%-75% of DeltaHr/Hr for 8-16-nm-thick media. An analysis of the temperature dependence of DeltaHr/Hr supported this conclusion. It is concluded that the SFD measured at VSM time scales is significantly influenced by Thermal Agitation of the magnetization, and the intrinsic SFD is likely to be nearly half that measured at VSM time scales

  • effect of Thermal Agitation on the switching field distributions of coptcr sio2 perpendicular recording media
    Journal of Applied Physics, 2006
    Co-Authors: T Shimatsu, H Muraoka, T Kondo, K Mitsuzuka, S Watanabe, Y Nakamura
    Abstract:

    The effect of Thermal Agitations on the switching field distribution (SFD) of CoPtCr–SiO2 perpendicular media was investigated. Dc demagnetizing (DCD) magnetization curves and minor dc demagnetizing (M-DCD) magnetization curves were measured at applied field sweep rates of ∼10 and ∼108Oe∕s. We estimated the SFD from the difference between the DCD and M-DCD curves, and defined them as ΔHr∕Hr (at ∼10Oe∕s) and ΔHrP∕HrP (at ∼108Oe∕s). The values of ΔHrP∕HrP were found to be 60%–70% of ΔHr∕Hr. The difference between ΔHrP∕HrP and ΔHr∕Hr should be caused by Thermal Agitation of the magnetization. The influence of the distribution of the Thermal Agitation on SFD was calculated using the distribution of the grain volumes. It is concluded that the SFD measured at vibrating-sample magnetometer (VSM) time scales is significantly influenced by Thermal Agitation of the magnetization, and reduction of the grain size distribution is the most effective way to reduce the SFD at VSM time scales.