| Project/Area Number |
13440109
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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 |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TAKAGI Hidenori The University of Tokyo, Graduate School of Frontier Sciences, Professor, 大学院・新領域創成科学研究科, 教授 (40187935)
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| Co-Investigator(Kenkyū-buntansha) |
SASAGAWA Takao The University of Tokyo, Graduate School of Frontier Sciences, Research associate, 大学院・新領域創成科学研究科, 助手 (30332597)
HANAGURI Tetsuo The University of Tokyo, Graduate School of Frontier Sciences, associate Professor, 大学院・新領域創成科学研究科, 助教授 (40251326)
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| Project Period (FY) |
2001 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥15,400,000 (Direct Cost: ¥15,400,000)
Fiscal Year 2003: ¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2002: ¥4,100,000 (Direct Cost: ¥4,100,000)
Fiscal Year 2001: ¥8,600,000 (Direct Cost: ¥8,600,000)
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| Keywords | Mott insulator / physics of Semiconductor Devices / Carrier Doping / nano-scale variation of electronic / charge ordering / Field Effect Transistor (FET) Structure / transition metal oxides. / 電荷効果トランジスタ / モット半導体 / キャリアドーピグ / Ca_<2-x>Na_xCuO_2Cl_2 / 電界効果型トランジスタ(FET) / SrTiO_3 / 強相関エレクトロニクス / 強相関半導体 / ドーピング / Ca_2CuO_2Cl_2 / ケミカルポテンシャルシフト / 磁性-誘電結合 |
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| Research Abstract |
The aim of this research project is to explore the device physics of strongly correlated semiconductors. One of the major targets was the impurity effect. As a prototypical system, lightly doped Mott insulator Ca_<2-x>Na_xCuO_2Cl_2 was studied. We found a non-scale self-organization of electrons associated with doping by STM/STS and finally identified it as a checkerboard type charge ordering, which we believe is at the heart of cuprate physics including large psedo-gap phenomena. We also find nano-scale variation of electronic states around the impurities in nearly ferromagnetic ruthenates, which represents an important step to establish physics of impurity states in strongly correlated electron systems. The other major targets was fabrication of oxide device, in particular field effect transistor (FET). We have successfully fabricated SrTiO_3 perovskite FET, which shows well defined FET characteristics such as the saturation of drain current. Even better performance was achieved in another perovskite oxide KTaO_3, which showed ON/OFF rationof 1000 and the field effect mobility of 0.4 cm^2/Vsec comparable with those of organic FET. These devices can work at a cryogenic temperature as low as 2K and the presence of metallic channel was confirmed. These results opened door for FET "chemistry" of exotic transition metal oxides.
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