| Project/Area Number |
09244103
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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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| Research Institution | Tohoku University |
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Principal Investigator |
OHNO Hideo Research Institute of Electrical Communication, Tohoku University Professor, 電気通信研究所, 教授 (00152215)
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| Co-Investigator(Kenkyū-buntansha) |
TARUCHA Seigo Department of Physical, University of Tokyo, Professor, 大学院・理学系研究科, 教授 (40302799)
SUZUKI Naoshi Department of Physical Science, Graduate School of Engineering Science, Osaka University, Professor, 大学院・基礎工学研究科, 教授 (40029559)
KATSUMOTO Shingo Institute for Solid Physics, University of Tokyo, Professor, 物性研究所, 助教授 (10185829)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥168,500,000 (Direct Cost: ¥168,500,000)
Fiscal Year 1999: ¥35,500,000 (Direct Cost: ¥35,500,000)
Fiscal Year 1998: ¥61,300,000 (Direct Cost: ¥61,300,000)
Fiscal Year 1997: ¥71,700,000 (Direct Cost: ¥71,700,000)
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| Keywords | Diluted magnetic semiconductor / ab initio calculation / spin / Spin relaxation / Artificial atom / Metal / insulator transition / Giant magnetoresistance / Kondo effect / (Ga,Mn)As / アニール効果 / kp摂動 / スピン注入 / 人工分子 / 磁気異方性 / バルクハウゼンジャンプ / 異方性磁気抵抗 / 第一原理電子状態計算 / 人工原子(分子) / RKKY相互作用 / sp-d交換相互作用 / 金属絶縁体遷移(リエントラント) |
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| Research Abstract |
This group was formed to study and elucidate the electronic structure and the transport properties of spin-controlled semiconductoring materials and nanostructures. To this end, the growth and processing of ferromagnetic semiconductors and their related heterostructures, transport/magnetic/optical properties of these materials and structures, and the electronic structure calculation as well as the theory of transport properties were investigated. The summary of the research results is :
1. Ferromagnetic/non-magnetic trilayer structures made of semiconductor showed spin-dependent scattering, interlayer coupling and tunneling magnetoresistance. Resonant tunneling diodes with (Ga, Mn) As emitter exhibited spontaneous current peak splitting below the ferromagnetic transition temperature. Also electrical spin-injection from ferromagnetic (Ga, Mn) As into a nonmagnetic GaAs structure was demonstrated. (H.Ohno et al.)
2. Magnetism and transport in (In, Mn) As and (Ga, Mn) As at low temperature was studied. One of our important finding is that crystalline quality is much improved by heat treatment at comparatively low temperature. Soft X-ray absorption experiment is making it clear that the improvement is due to the evaporation of excess As atoms. (S.Katsumoto et al.)
3. First-principle electronic band-structure calculations are carried on III-V based diluted magnetic semiconductors (Ga, Mn) As. The magnetic interactions between the nearest neighboring 3d transition-metal spins are ferromagnetic for V, Cr, Mn. (N.Suzuki et al.)
We have prepared an artificial atom/molecular having a high-degree of rotational symmetry. For artificial atom, (i) atom-like properties such as shell filling and obeisance of Hund's rule and (ii) various transitions of spin states as a function of magnetic field have been observed. For artificial molecules we have investigated novel spin effects such as spin blockade, isospin blockade, spin-dependent tunneling, and so on. (Tarucha et al.)
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