| Project/Area Number |
17540306
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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 |
Condensed matter physics I
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| Research Institution | National Institute for Materials Science |
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Principal Investigator |
GOTO Atushi National Institute for Materials Science, Advanced Nano-Characterization Center, Senior Researcher (30354369)
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| Co-Investigator(Kenkyū-buntansha) |
SHIMIZU Tadashi National Institute for Materials Science, Advanced Nano-Characterization Center, Group Leader (00354366)
HASHI Kenjiro National Institute for Materials Science, Advanced Nano-Characterization Center, Senior Researcher (00321795)
飯島 隆広 京都大学, 大学院・理学研究科, 研究員 (20402761)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,690,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2007: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2006: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2005: ¥700,000 (Direct Cost: ¥700,000)
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| Keywords | Semiconductor Physics / Spin Electronics / Optical Properties / Nuclear Maenetic Resonance / Optical Pumping / Dynamic Nuclear Polarization / Cross Polarization |
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| Research Abstract |
The aim of the project is to elucidate the nature of dynamic nuclear polarizations and the resultant hyperpolarized nuclear spins in compound semiconductors. The project started in April 2005, and the first two years (2005-2006) were devoted to developing a system for the study. As a result, we successfully developed an optical pumping double resonance system, which enables simultaneous irradiations of infrared light for optical pumping and two-channel rf''s for double resonance NMR at low temperatures and high magnetic fields. With the system developed, we performed a series of experiments to examine electron-nuclear and heteronuclear polarization transfer processes in optically-pumped compound semiconductors. Among them are measurements and analyses of cross-polarizations (CP) in Fe-doped semi-insulating InP under the optical pumping conditions. A wafer sample was set with the crystalline (100) plane normal to the magnetic field. While applying circularly-polarized infrared light to the sample surface, a series of CP experiments was performed between 31P and 115In. The cross-relaxation times thus obtained were analyzed by assuming a Gaussian form for the x-component of a cross-polarization spectral density. The analysis revealed that the cross-relaxation times are too short to account for by nuclear dipolar couplings. This indicates the presence of indirect couplings mediated by electron spins. In a similar analysis, we showed that the indirect couplings of the order of 1 kHz can explain the experimental observation. The data also provided information on the anisotropy of the indirect couplings.
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