2007 Fiscal Year Final Research Report Summary
Study on dynamic nuclear polarization and hyperpolaeized nuclear spins in compound semiconductors
| 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)
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| Project Period (FY) |
2005 – 2007
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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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[Presentation] 半導体用の動的核偏極技術の開発II2007
Author(s)
後藤 敦、加藤誠一、大木 忍、端健二郎、清水 禎
Organizer
第41/6回固体NMR・材料フォーラム
Place of Presentation
東京大学(東京都)
Year and Date
2007-05-08
Description
「研究成果報告書概要(和文)」より
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[Presentation] 半導体用の動的核偏極技術の開発2006
Author(s)
後藤 敦、端健二郎、清水 禎、大木 忍
Organizer
平成18年度ナノ計測センター研究成果発表会
Place of Presentation
物質・材料研究機構(つくば市)
Year and Date
2006-10-27
Description
「研究成果報告書概要(和文)」より
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