| Project/Area Number |
19360290
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical properties of metals
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| Research Institution | Japan Atomic Energy Agency |
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Principal Investigator |
SAKAI Seiji Japan Atomic Energy Agency, 先端基礎研究センター, 研究副主幹 (10354929)
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| Co-Investigator(Kenkyū-buntansha) |
MITANI Seiji 物質材料研究機構, 磁性材料センター, グループリーダー (20250813)
BABA Yuji 日本原子力研究開発機構, 量子ビーム応用部門, グループリーダー (90360403)
AVRAMOV Pavel Kirensky Institute of Physics, 教授 (00414582)
MATSUMOTO Yoshihiro 日本原子力研究開発機構, 先端基礎研究センター, 研究員 (80455287)
ENTANI Shiro 日本原子力研究開発機構, 先端基礎研究センター, 博士研究員 (40549664)
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| Project Period (FY) |
2007 – 2009
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| Project Status |
Completed (Fiscal Year 2009)
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| Budget Amount *help |
¥16,770,000 (Direct Cost: ¥12,900,000、Indirect Cost: ¥3,870,000)
Fiscal Year 2009: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
Fiscal Year 2008: ¥6,630,000 (Direct Cost: ¥5,100,000、Indirect Cost: ¥1,530,000)
Fiscal Year 2007: ¥7,930,000 (Direct Cost: ¥6,100,000、Indirect Cost: ¥1,830,000)
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| Keywords | ナノ物性 / フラーレン / 遷移金属 / ナノ粒子 / 磁気抵抗 / スピントロニクス / 有機分子 / スピン偏極 / 分子スピントロニクス / 界面 / 磁気抵抗効果 / トンネル磁気抵抗効果 / トンネル効果 / スピン注入 / フフーレン |
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| Research Abstract |
Systematic studies were conducted on the giant TMR effect found in the fullerene(C_<60>)-cobalt(Co) granular thin films, which are composed of a C_<60>-Co compound matrix and Co nanoparticles precipitated therein. It was revealed that the C_<60>-Co films show TMR ratios as high as several 100%-1000% reflecting the dispersion state of Co nanoparticles which can be control by the sample composition. Synchrotron X-ray absorption and magnetic circular dichroism studies clarified that there exist localized d-spins in the C_<60>-Co compound matrix, and the localized spins have a predominant effect on the temperature dependence of the TMR magnitude. It was clarified from the analysis of the electrical and TMR properties of the devices with a nano-layered structure that the giant TMR effect at low temperatures is due to higher-order cotunnleing process, which is related to the granular structure of the films, and, more importantly, due to nearly-complete spin polarization (higher than 80% at zero temperature and bias) of tunneling electrons generated at the interface of Co nanoparticle and the C_<60>-Co compound. The nearly-complete spin polarization of tunneling electron is indicated to be a characteristic nature of the present hybrid system realized under the condition of well defined granular structure and independent of device structure.
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