量子点体系的电子自旋输运

发布时间：2018-07-03 12:05

本文选题：介观系统 + 量子器件　；参考：《湖南大学》2015年硕士论文

【摘要】：随着新兴技术的发展,越来越多的纳米量子器件已经被研发出来。由于体系的输运性质决定了器件的特性,因而输运性质的研究具有重要的理论研究意义和潜在的应用价值。目前介观体系的量子自旋输运研究是凝聚态物理中十分活跃的前沿研究领域之一。它不但揭示出一系列重要的物理内禀,同时也呈现出广阔的应用前景。本论文的研究内容围绕量子点体系内的自旋输运性质进行,主要包括如下四个方面,细节如下:第一章:介绍了介观体系的研究背景及现状,量子器件的发展,自旋电子器件及其应用,介观尺度下特别是量子点体系中的自旋极化输运性质。简单介绍了处理介观体系输运问题时人们主要采用的几种方案。第二章:介绍了一些介观体系输运研究用到的基本理论,主要介绍了Buttiker散射矩阵理论,非平衡态格林函数方法,Master方程。并且简单介绍了这些基本定义和理论在量子点体系中的运用。第三章:为了在自旋电子器件中实现有效的自旋注入,完全极化流或纯自旋流(即不带有电荷流)作为有效的方法被广泛地研究。近年来,三端自旋器件被广泛地用来产生完全极化流或纯自旋流。我们采用非平衡态格林函数方法,研究了一个铁磁(FM)端和两个非磁性半导体(SC)端与一个量子点耦合组成的一个三端量子点体系的自旋输运性质。结果显示当调节某一非磁性半导体端的外部电压在一个合适的范围,在另一个非磁性半导体端会出现纯自旋流平台和完全极化流平台,并且在一个大的外部电压变化范围内平台都不会消失。第四章:我们还进一步从理论上研究了一些参数包括温度tkB,门电压控制的量子点能级0?和其它端的端电压对纯自旋电子流平台和完全极化流平台的影响。我们发现参数的变化对SC1端的纯自旋电子流平台和完全极化流平台有相当大的影响。因为这些参数的变化往往不可避免,所以我们进而研究了这些参数的变化对纯自旋流平台的影响的补偿。我们通过调节其它参数值来抵消某一个参数的变化对产生纯自旋流平台带来的影响。此外,为了让我们的研究结果更具普遍性,我们采用了不同的器件参数且也得到了类似的结论。最后对本论文的工作进行了总结。
[Abstract]:With the development of new technology, more and more nano quantum devices have been developed. Because the transport properties of the system determine the characteristics of the devices, the study of transport properties has important theoretical research significance and potential application value. The study of quantum self rotation transport in mesoscopic system is very active in condensed matter physics One of the frontier research fields. It not only reveals a series of important physical intrinsic endowments, but also presents a broad application prospect. The research content of this thesis focuses on the spin transport properties in the quantum dot system, including the following four aspects, the details are as follows: Chapter 1: the research background and status of mesoscopic system, quantum The development of devices, spintronic devices and their applications, the spin polarization transport properties of the mesoscopic scale systems, especially in quantum dots, are introduced briefly. In the second chapter, the basic theories used in the transport study of mesoscopic systems are introduced, and the Buttiker scattering is mainly introduced. Matrix theory, nonequilibrium Green function method and Master equation. And the application of these basic definitions and theories in quantum dot system is briefly introduced. The third chapter is that in order to achieve effective spin injection in spintronic devices, full polarization flow or pure spin flow (i.e. without charge flow) is widely studied as an effective method. In recent years, three terminal spin devices have been widely used to produce complete polarization flow or pure spin flow. We have studied the spin transport properties of a three terminal quantum dot system consisting of a ferromagnetic (FM) end and two nonmagnetic semiconductor (SC) ends coupled with a quantum dot using the nonequilibrium Green function method. The external voltage of the nonmagnetic semiconductor end is in a suitable range, and there will be a pure spin flow platform and a fully polarized flow platform at the other non magnetic semiconductor end, and the platform will not disappear in a large external voltage range. Fourth chapter: we further theoretically study some parameters including the temperature tkB, the gate power. The effect of the pressure controlled quantum point energy level 0? And the end voltage of other ends on the pure spintronic flow platform and the fully polarized flow platform. We found that the changes in the parameters have considerable influence on the pure spintronic and fully polarized flow platforms at the SC1 end. Because these parameters are inevitable, we have further studied this Some parameters are compensated for the effect of the pure spin flow platform. We counteract the effect of the change of one parameter on the pure spin flow platform by adjusting the other parameter values. In addition, in order to make our results more universal, we have adopted different device parameters and obtained similar conclusions. The work of the paper is summarized.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O471.1

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