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.

该研究的目的是建立自旋电子器件的基础技术，其中信息是通过自旋产生和处理的。在这里，我们设计并制造了铁磁/非磁半导体量子结构，并通过用电学和光学手段控制载流子、核、激子和磁性离子的自旋态来研究这些结构中独特的光学、电学和磁学性质。研究成果概括如下： 1.证明了p铁磁/n^+非磁半导体隧道结电电子自旋注入效率敏感地依赖于n^+-GaAs的厚度和掺杂浓度2.利用时间分辨法拉第旋转技术研究了n-GaAs/AlGaAs(110)量子阱中各向异性g因子和超精细相互作用的影响。我们观察到动态核极化的双稳定性和滞后现象，通过自洽计算很好地再现了这些现象。我们还评估了动态核极化程度为30%。3.我们证明了可以通过改变门控n-GaAs/AlGaAs中的背景电子密度来控制超精细相互作用和动态核极化（110）量子井。我们表明，实验观察可以用金属-绝缘体转变来解释，超精细相互作用敏感地依赖于金属-绝缘体转变。