Electronic Properties of Spin Controlled Semiconductor Nanostructures

自旋控制半导体纳米结构的电子特性

基本信息

批准号：
09244103
负责人：
OHNO Hideo
金额：
$ 107.84万
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：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

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.)

该小组的成立是为了研究和阐明自旋控制半导体材料和纳米结构的电子结构和输运特性。为此，研究了铁磁半导体及其相关异质结构的生长和加工，这些材料和结构的输运/磁/光性质，以及电子结构计算和输运性质理论。研究结果概括如下： 1．由半导体制成的铁磁/非磁三层结构表现出自旋相关散射、层间耦合和隧道磁阻。具有 (Ga, Mn) As 发射极的谐振隧道二极管在铁磁转变温度以下表现出自发电流峰值分裂。还演示了从铁磁性 (Ga, Mn) As 到非磁性 GaAs 结构的电自旋注入。（H.Ohno 等人）2。研究了(In,Mn)As和(Ga,Mn)As在低温下的磁性和输运。我们的重要发现之一是，通过在相对较低的温度下进行热处理，晶体质量大大提高。软X射线吸收实验清楚地表明，这种改善是由于多余As原子的蒸发所致。（S.Katsumoto 等人）3．第一原理电子能带结构计算是在 III-V 基稀磁半导体 (Ga, Mn) As 上进行的。对于 V、Cr、Mn，最近相邻的 3d 过渡金属自旋之间的磁相互作用是铁磁性的。 (N.Suzuki等人)我们制备了具有高度旋转对称性的人造原子/分子。对于人造原子，已经观察到（i）类似原子的性质，例如壳填充和遵循洪德规则，以及（ii）作为磁场函数的自旋态的各种转变。对于人造分子，我们研究了新的自旋效应，例如自旋封锁、同位旋封锁、自旋相关隧道效应等。（塔鲁查等人）