| Project/Area Number |
11650697
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Inorganic materials/Physical properties
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| Research Institution | OKAYAMA UNIVERSITY |
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Principal Investigator |
FUJII Tatsuo Okayama University, Graduate School of Natural Science and Technology, Associate Professor, 自然科学研究科, 助教授 (10222259)
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| Co-Investigator(Kenkyū-buntansha) |
NAKANISHI Makoto Okayama University, Faculty of Engineering, Assistant, 工学部, 助手 (10284085)
TAKADA Jun Okayama University, Graduate School of Natural Science and Technology, Professor, 自然科学研究科, 教授 (60093259)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2000: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1999: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | oxide magnetic semiconductor / iron oxides / ilumenite / solid solution / exchange coupling films / spin-flip / epitaxial thin films / helicon sputtering / ヘマタイト / 非化学量論性 / 磁気抵抗効果 / エビタキシャル薄膜 / 交換結合 / 磁性半導体 / コバルトフェライト |
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| Research Abstract |
Magnetic semiconductors are one of die promising electronics materials for the next generation, so-called spintronics materials. In this research we proposed a novel technique to control the spin-polarized transport of magnetic semiconductors and tried to realize it. The first subject was to develop thin films of new oxide magnetic semiconductors focused on a hematite-ilumenite solid solution system having a high spin polarization at room temperature. There had been many difficulties to prepare well-defined hematite ilumenite solid solution films having good magnetic semiconductive properties, because they had many controllable factors such as an order-disorder transition and Fe^<2+>/Fe^<3+> mixed valence states, etc. We found optimized preparation conditions for the solid solution films by helicon sputtering to control remanent oxygen pressure and substrate temperature precisely. The films showed magnetic semiconductive properties such as magnetoresistance at room temperature. The second subject was to control magnetic structures of ferromagnetic layers by means of a spin-flip transition of antiferromagnetic layers. Only epitaxial hematite films showed a unique spin-flip transition. We prepared hematite/spinel ferrite bilayered films by helicon sputtering and surveyed magnetic properties around the spin-flip transition. The spin-flip transition in a hematite layer disappeared because of a large in-plane magnetic anisotropy of a spinel ferrite layer. We first found the 90° exchange coupling between oxide magnetic layers. Unfortunately we could not realize the proposing spin control technique, but we could obtain huge results concerning preparation techniques for well-defined iron oxide films and their structural, magnetic and electronic properties.
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