| Project/Area Number |
15360192
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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 |
Electron device/Electronic equipment
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
MATSUYAMA Kimihide Kyushu University, Faculty of Information Science and Electrical Engineering, Professor, 大学院・システム情報科学研究院, 教授 (80165919)
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| Co-Investigator(Kenkyū-buntansha) |
NOZAKI Yukio Kyushu University, Faculty of Information Science and Electrical Engineering, Research associate, 大学院・システム情報科学研究院, 助手 (30304760)
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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 |
¥10,300,000 (Direct Cost: ¥10,300,000)
Fiscal Year 2005: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2004: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 2003: ¥7,000,000 (Direct Cost: ¥7,000,000)
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| Keywords | Spintronics / Nonvolatile memory / Field programmable logic device / MRAMs / 不揮発メモリ |
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| Research Abstract |
Experimental and numerical studies on a novel device concept of sharing function have been performed to realize a magnetic nonvolatile memory with terabit density and high access speed. In the proposed cell structure, data storage layer for bit information carrier and switching layer for data writing are vertically integrated through magnetic coupling.
1)Two different functional integrating mechanism of dipole coupling and inter-layer exchange coupling have been compared by numerical simulation, and it was found that the exchange coupling exhibits superior torque transmitting from switching to storage layer in the fine cell.
2)A cross-point (CP) memory cell with the minimum pattern size of 200 nm was fabricated by a self-aligned process, where a magnetic mulilayer strip was structured with an over-laid conductor pattern used as a mask for dry-etching. Well defined dipole coupling was confirmed from magnetoresistive measurements for the fabricated CP cell, which leads to the drastic reduc
… More
tion of the magnetization reversal field.
3)Thermally assisted magnetization reversal was performed for an exchange coupled bi-layer cell, consisted of soft magnetic CoFe and hard magnetic TbFe layer. The current induced local Joule heating decreases the magnetic anisotropy in the TbFe layer, which results in the marked decrease of the magnetization reversal field of the bi-layer. A high speed operation was also confirmed with the pulsed laser heating.
4)Numerical analysis for the magnetization process at high temperature was carried out with the newly developed program introducing a macro scale model. Detailed mechanism of thermally assisted magnetization reversal in the exchange coupled bi-layer has been clarified. Magnetic properties, the layer structure and the inter-layer exchange coupling stiffness have been optimized to realize the superior functional sharing performance. Practical data stability and low power memory operation have been confirmed for the optimized perpendicularly magnetized cell with an order of 10 nm lateral dimension. Less
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