2005 Fiscal Year Final Research Report Summary
Design of opto-spintronics devices and nanospin-probes
| Project/Area Number |
14076214
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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 | Tohoku University |
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Principal Investigator |
SHIRAI Masafumi Tohoku Univiersity Research Institute of Electrical Communication, Professor, 電気通信研究所, 教授 (70221306)
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| Co-Investigator(Kenkyū-buntansha) |
MIURA Yoshio Tohoku University Research Institute of Electrical Communication, Research Associate, 電気通信研究所, 助手 (10361198)
NAGAO Kazutaka Tohoku University Research Institute of Electrical Communication, Research Associate, 電気通信研究所, 助手 (00361197)
KATAYAMA Hiroshi (YOSHIDA Hiroshi) Osaka University Institute of Scientific and Industrial Research, Professor, 産業科学研究所, 教授 (30133929)
SATO Kazunori Osaka University Institute of Scientific and Industrial Research, Research Associate, 産業科学研究所, 助手 (60379097)
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| Project Period (FY) |
2002 – 2005
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| Keywords | Spintronics / Materials design / First-principles calculation / Diluted magnetic semiconductor / Curie temperature / Half-metal / Spin polarization / Hetero-junction interface |
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| Research Abstract |
1. Diluted magnetic semiconductors (DMS) based on wide band-gap materials such as GaN and ZnO, which are exploited in optoelectronic device applications, have been designed theoretically on the basis of first-principles calculations. (1) The relative energy position and the degree of hybridization between the valence-band of host semiconductors and 3d orbitals of magnetic dopants are important to understand the mechanism of ferromagnetism in DMS. (2) The Curie temperature of DMS has been evaluated accurately by accounting the exchange interaction between localized spins in DMS as a function of the inter-atomic distance. Room-temperature ferromagnetism is hardly achieved for wide band-gap DMS since the exchange interaction is rather short-ranged. (3) The inhomogeneous distribution of magnetic dopants is expected in DMS due to attractive interaction between them. (4) The increase of Curie temperature is expected for DMS co-doped with non-magnetic elements appropriately. (5) The ferromagnetism could be obtained by doping non-magnetic elements appropriately into certain semiconductors.
2. Half-metallic ferromagnets exhibiting high spin polarization have been designed theoretically on the basis of first-principles calculations. (1) Zinc-blende CrAs and CrSb are promising materials for spintronic device applications since they are compatible with semiconductors exploited in conventional electronic devices. (2) The influence of atomic disorder in half-metallic Heusler alloys has been examined theoretically. High spin polarization is maintained even in the B2-type disordered structure. (3) The electronic structure of hetero-junctions between half-metallic ferromagnets and semiconductors has been investigated. High spin polarization is preserved for the (110) interface between Heusler alloys And AArnientichirtnrAAC wAll As fnr 7inn-h17onda Or Ac/carninnndiinfnr inforfanne
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