| Project/Area Number |
15206074
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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 |
Structural/Functional materials
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| Research Institution | Tohoku University |
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Principal Investigator |
INOMATA Koichiro Tohoku University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (90323071)
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| Co-Investigator(Kenkyū-buntansha) |
TEZUKA Nobuki Tohoku University, Graduate School of Engineering, Research Associate, 大学院・工学研究科, 助手 (40323076)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥50,700,000 (Direct Cost: ¥39,000,000、Indirect Cost: ¥11,700,000)
Fiscal Year 2005: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2004: ¥14,170,000 (Direct Cost: ¥10,900,000、Indirect Cost: ¥3,270,000)
Fiscal Year 2003: ¥31,720,000 (Direct Cost: ¥24,400,000、Indirect Cost: ¥7,320,000)
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| Keywords | Synthetic antiferromagnets / Ru / Spin injection switching / Thermal stability / Magnetic tunnel junction / CPP-GMR / スピン注入 / 磁化反転 / 反平行結合膜 / スピン反転 / ナノサイズ / 磁性素子 / MRAM / トンネル磁気抵抗効果 / 磁区構造 |
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| Research Abstract |
We have reported that the synthetic antiferromagnet can realize the size-independent spin switching. The synthetic antiferromagnet is also expected to be superior in the thermal stability due to its volume effect. On the other hand, the spin injection magnetization switching (CIMS) has been developed as a low current spin switching method of the nano-size magnetic element. In this study, we have investigated the CIMS of the synthetic antiferromagnet.
The CPP-GMR elements with a Co_9Fe/Ru/Co_9Fe synthetic antiferromagnet free layer with 0.45nm thick Ru were sputter-deposited on a thermally oxidezed Si substrate using the sputtering, which were microfabricated into submicron size using the electron beam lithography and Ar ion etching. The Co_9Fe single layer film is also fabricated. We have found that the critical current density for the spin injection switching is reduced by using the synthetic antiferromagnet due to the spin filtering effect of Ru. On the other hand, we have investigated the thermal stability of the magnetic tunnel junctions with a synthetic antiferromagnet free layer by estimating the K_uV/k_BT from the measument of the sweep-rate -dependent coercivity for defferent aspect rations of the elements. We have found the better thermal stability of the synthetic antiferromagnet with lower aspect ratios than that of the single layer. Thus, we conclude the synthetic antiferromagnet free layers are hopeful for nano-size magnetic elements used for such as the memory elements of the high density MRAM.
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