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Spin injection and spin control in magnetic/non-magnetic semiconductor quantum structures

磁性/非磁性半导体量子结构中的自旋注入和自旋控制

基本信息

批准号：
14205002
负责人：
OHNO Yuzo
金额：
$ 27.12万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

The purpose of the research is to establish fundamental technology for spintronics devices in which information is born and processed by spins. Here, we designed and fabricated ferromagnetic/non-magnetic semiconductor quantum structures and investigated the unique optical, electrical, and magnetic properties in those structures by controlling the spin states of carriers, nuclei, excitons, and magnetic ions with electrical and optical means. The achievements of the research are summarized as :1.We manifested that the efficiency of electrical electron spin injection in p-ferromagnetic/n^+-non-magnetic semiconductor tunnel junction sensitively depends on the thickness and doping concentration of n^+-GaAs interface layer by performing a systematic experiments, and showed the optimized condition.2.We studied the effect of anisotropic g-factor and hyperfine interaction in n-GaAs/AlGaAs (110) quantum wells by time-resolved Faraday rotation technique. We observed bistability and hysteresis of dynamic nuclear polarization, which were well reproduced by self-consistent calculation. We also evaluated the degree of dynamic nuclear polarization to be 30%.3.We demonstrated that the hyperfine interaction and dynamic nuclear polarization can be controlled by changing the background electron density with gate electric field in a gated n-GaAs/AlGaAs (110) quantum well. We showed that the experimental observation can be explained by metal-insulator transition, on which the hyperfine interaction depends sensitively.

这项研究的目的是为自旋电子学设备建立基础技术，在其中通过自旋来产生和处理信息。在这里，我们设计和制备了铁磁/非磁性半导体量子结构，并通过电学和光学手段控制载流子、原子核、激子和磁性离子的自旋态，研究了这些结构中独特的光学、电学和磁学性质。本论文的研究成果概括如下：1.通过系统的实验，证明了p-铁磁/n^+-非磁性半导体隧道结中电子的自旋注入效率敏感地依赖于n^+-GaAs界面层的厚度和掺杂浓度，并给出了优化的条件。2.利用时间分辨Faraday旋转技术研究了n-GaAsAlGaAs110量子阱中各向异性g因子和超精细相互作用的影响。我们观察到了动态核极化的双稳态和滞后性，通过自洽计算很好地再现了这两个现象。3.我们证明了门控n-GaAs/AlGaAs(110)量子阱中的超精细相互作用和动态核极化可以通过改变栅电场的背景电子密度来控制。结果表明，实验观察可以用金属-绝缘体相变来解释，而超精细相互作用依赖于金属-绝缘体相变。