2005 Fiscal Year Final Research Report Summary
Manipulation of ferromagnetically coupled spin system with light and its applications
| Project/Area Number |
14076210
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
MUNEKATA Hiroo Tokyo Institute of Technology, Graduate School of Science and Engineering, Professor, 大学院理工学研究科, 教授 (60270922)
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| Co-Investigator(Kenkyū-buntansha) |
KOSHIHARA Shinya Tokyo Institute of Technology, Graduate School of Science and Engineering, Professor, 大学院理工学研究科, 教授 (10192056)
KONDO Thuyoshi Tokyo Institute of Technology, Graduate School of Science and Engineering, Assistant Professor, 大学院理工学研究科, 助手 (70323805)
MATSUDA Yasuhiro Okayama University, Faculty of Science, Associate Professor, 理学部, 助教授 (10292757)
OIWA Akira University of Tokyo, Graduate School of Engineering, Lecturer, 工学系研究科, 講師 (10321902)
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| Project Period (FY) |
2002 – 2005
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| Keywords | spintronics / ferromagnetic semiconductors / spin-dependent optical phenomena / spin dynamics / carrier-mediated ferromagnetism / light-induced magnetism / cooperative Phenomena / magnetic-semiconductor hybrid structures |
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| Research Abstract |
(1) Ferromagnetic semiconductors
Effect of nitrogen doping in (Ga,Mii)As epitaxial films was investigated aiming at controlling Curie temperature Tc during the growth process. Two effects were found : firstly, inducement of perpendicular magnetic anisotropy due to a slight lattice shrinkage ; secondly, reduction of Tc due to the localization of hole carriers. The growth method to enhance Mn contents, with post annealing, was developed successfully, which resulted in highest Curie temperature of Tc = 90 K for (In,Mn)As.
(2) light-induced precessions of magntization
Well controlled experiments and analysis with LLG equations were carried out to elucidate light-induced precession in (Ga,Mri)As. It became clear that optical excitation induced a change in magnetic anisotropy, which caused a change in an effective magnetic and thus precession. It was concluded that the observed phenomenon is caused not by the light-induced increase in temperate but by the optical excitation.
(3) Direct observation of light-induced rotation of magnetization
The development of scanning laser magneto-optical microscope has reached at the stage of testing its performance with (Ga,Mn)As. Domain structures of the in-plane magnetization was observed successfully. Direct imaging of magnetization rotation induced by circularly-polarized light was achieved for the first time. That unpolarized light did not cause rotation strongly suggested that this phenomenon was not induced by the light-induced heating of samples.
(4) Spin photovoltaic effect
A n-AlGaAs/p-InGaAs heterostructure diode showing relatively large circularly-polarized-light-dependent photocurrent (>50 nA) was demonstrated successfully for the first time. Theoretical analysis using both heterojunction transport and solar cell model accommodating MCD-effect was also developed, by which importance of discontinuity in band edge profile was discussed quantitatively.
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Research Products
(44 results)
