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Design of opto-spintronics devices and nanospin-probes

光自旋电子学器件和纳米自旋探针的设计

基本信息

批准号：
14076214
负责人：
SHIRAI Masafumi
金额：
$ 27.46万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2005
项目状态：
已结题

项目摘要

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

1.在第一性原理计算的基础上，从理论上设计了用于光电子器件开发的GaN、ZnO等宽禁带材料的稀磁半导体。(1)主体半导体的价带与磁性掺杂的3d轨道之间的相对能量位置和杂化程度对于理解DMS中的铁磁性机制是重要的。(2)通过计算DMS中局域自旋之间的交换作用作为原子间距离的函数，准确地计算了DMS的居里温度。对于宽禁带DMS，由于交换作用范围较短，很难实现室温铁磁性。(3)在DMS中，由于磁性杂质之间相互吸引的相互作用，它们的分布可能是不均匀的。(4)适当共掺非磁性元素的DMS的居里温度有望提高。(5)在某些半导体中适当掺杂非磁性元素可以获得铁磁性。在第一性原理计算的基础上，从理论上设计了具有高自旋极化特性的半金属铁磁体。(1)闪锌矿CrAs和CrSb与传统电子器件中的半导体材料兼容，是一种很有前途的自旋电子器件材料。(2)从理论上考察了原子无序对半金属Heusler合金的影响。即使在B2型无序结构中也能保持较高的自旋极化。(3)研究了半金属铁磁体与半导体异质结的电子结构。对于Heusler合金和AArnientichirtnrAAc壁之间的(110)界面，高自旋极化被保留为FNR7inn-H17onda或Ac/Carnnndiinnr inforfanne