2005 Fiscal Year Final Research Report Summary
THEORY OF SPIN-DEPENDENT TRANSPORT IN HYBRID NANOSTRUCTURES
| Project/Area Number |
15540328
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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 II
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
TAKAHASHI Saburo TOHOKU UNIVERSITY, INSTITUTE FOR MATERIALS RESEACH, RESEARCH ASSOCIATE, 金属材料研究所, 助手 (60171485)
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| Co-Investigator(Kenkyū-buntansha) |
MAEKAWA Sadamichi TOHOKU UNIVERSITY, INSTITUTE FOR MATERIALS RESEACH, PROFESSOR, 金属材料研究所, 教授 (60005973)
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| Project Period (FY) |
2003 – 2005
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| Keywords | SPIN INJECTION / NONLOCAL SPIN TRANSPORT / CROSSED ANDREEV REFLECTION / QUBIT / πJUNCTION / MAGNETIC SEMICONDUCTOR / SPIN HALL EFFECT / DOMAIN WALL MOTION |
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| Research Abstract |
1.We studied the nonlocal spin transport in a device consisting of a nonmagnetic metal (N) and ferromagnetic injector and detector electrodes connected to N. We solve the spin-dependent transport equations in a device with arbitrary interface resistance, and obtain the optimal conditions for efficient spin injection, accumulation, and spin transport in the device. We proposed a nonlocal spin manipulation by using the nonlocal spin-current injection technique.
2.We studied the nonlocal Andreev reflection in a device consisting of two ferromagnetic wires attached to a superconductor, and clarified the range over which the crossed Andreev reflection takes place.
3.We proposed a new superconducting qubit which consists of a superconducting ring with ferromagnetic junctions and an ordinary Josephson junction. A quantum coherent two-level state is formed without an external magnetic field. This feature makes it possible to reduce the size leading to a long decoherence time.
4.We studied the electronic structure of a magnetic impurity and the ferromagnetic interaction between magnetic impurities in a semiconductor using the Haldane-Anderson model, and obtain a long-range ferromagnetic exchange interaction between the localized moments due to the overlapping of the extended spin densities around the impurities.
5.We proposed a method for estimating the strength of spin-orbit scattering by impurities in non-magnetic metals. We show that the pure spin current created by the nonlocal spin-injection technique produces a nonlocal Hall voltage, which is measurable by experiments.
6.We constructed a microscopic theory describing the interaction between spin current and a domain wall, and presented new equations of motion for domain walls. We proposed nano-structured magnetic memories utilizing the current-driven domain wall motion.
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[Journal Article] スピン注入2003
Author(s)
前川 禎通
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Journal Title
月間「マテリアルインテグレーション」 特集 スピントロニクス(ティー・アイ・シィー) 16
Pages: 29-34
Description
「研究成果報告書概要(和文)」より
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