| Project/Area Number |
11305027
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| Research Category |
Grant-in-Aid for Scientific Research (A).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
電子デバイス・機器工学
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| Research Institution | Tohoku University |
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Principal Investigator |
NAKAMURA Yoshihisa Res.Inst.of Electrical Communication, Tohoku University, professor, 電気通信研究所, 教授 (50006235)
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| Co-Investigator(Kenkyū-buntansha) |
WATANABE Isao Res.Inst.of Electrical Communication, Tohoku University, research associate, 電気通信研究所, 助手 (10302233)
SHIMATSU Takehito Res.Inst.of Electrical Communication, Tohoku University, research associate, 電気通信研究所, 助手 (50206182)
MURAOKA Hiroaki Res.Inst.of Electrical Communication, Tohoku University, professor, 電気通信研究所, 教授 (20239479)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥41,000,000 (Direct Cost: ¥41,000,000)
Fiscal Year 2000: ¥6,000,000 (Direct Cost: ¥6,000,000)
Fiscal Year 1999: ¥35,000,000 (Direct Cost: ¥35,000,000)
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| Keywords | High density magnetic recording / Perpendicular magnetic recording / Spin cluster / Nucleation-type of recording media / Remanence coercivity / Thermal stability / Perpendicular magnetic anisotropy |
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| Research Abstract |
Magnetic and structural properties of perpendicular recording media required to achieve both high thermal stability and low-noise performance are discussed. Moreover magnetic properties and recording performances of granular-amorphous hybrid media are examined.
(1) The angular dependence of remanence coercivity in CoCr based granular-type of perpendicular media indicated that magnetization reversal occurs by coherent rotation, and validates the use of an analysis based on the Stoner-Wohlfarth model.
(2) Experimental and theoretical analysis revealed that for CoCr based granular-type of perpendicular media of 20 nm thickness having the thermal stability factor K_uV/(kT)〜80, the maximum achievable value of the ratio of remanence coercivity to anisotropy field of grains, H_r/H_k, is 〜0.35. Furthermore, in order to realize a large squareness M_r/M_s of nearly 1.0, which is required to resist the thermal agitation effect at low recording density, we find that the value of perpendicular anisotropy, K_w is needs to be more than 3 times larger than the demagnetizing energy 2πM_s^2. X-ray diffraction patterns suggested that the suppression of structural imperfections in the hcp structure, particularly in the initial film growth, is the key issue to induce larger K_u value in the CoCr based granular-type of media.
(3) CoPrTb nucleation-type of amorphous film showed a large K_u value of 4x10^6 erg/cm^3 or more even at thin film of 10 nm. However, a large remanence coercivity was not successfully driven in CoPrTb single layer films.
(4) The ratio of signal to media-nose S/Nm of granular-amorphous hybrid media was about 10 dB higher than that of CoCr based granular-type of media (at 300 kFRPI). Moreover, the hybrid media showed extremely high thermal stability.
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