与铁磁引线耦合的半导体量子点中的生热性质研究

发布时间：2018-06-19 06:36

本文选题：量子点 + 电声子相互作用　；参考：《渤海大学》2015年硕士论文

【摘要】：本文运用非平衡格林函数方法研究量子点系统的生热特性,可为设计具有优良性能的量子器件提供模型参考和理论依据。本文第一章介绍介观系统和量子点的基本知识和非平衡格林函数方法,并阐述量子点生热性质的研究背景及意义。第二章研究与铁磁电极耦合的量子点的生热特性,发现当两个电极的磁矩方向相互平行时,总热量与电极的自旋极化率无关;当两个电极的磁矩方向相互反平行时,电极的铁磁性对生热的影响不同于对对电流的影响。在弱库仑作用和小偏压下,生热的强度随电极磁化率的增大而单调减小;反之,因自旋积累的作用,生热与电极自旋极化率呈非单调关系。本文第三章研究左右电极分别为铁磁体和普通金属的量子点系统中的生热特性。发现在库仑阻塞效应的影响下,电流在整个偏压范围内非单调变化。当铁磁电极中的自旋极化率不变时,正偏压下的热流极化率和电流极化率分别大于在负偏压时的数值。第四章研究与非共线性铁磁电极耦合的量子点中的生热特性。发现生热的强度在两个电极磁矩之间的夹角从0变化到错误!未找到引用源。的过程中单调增大,而电流却连续减小。生热的强度在不同的磁矩夹角情况下对电极的自旋极化率有不同的依赖关系。当两电极的磁矩处于非共线性且一个电极为半金属性时,生热的性质对自旋极化强度更加敏感。第五章给出了本文的结论。
[Abstract]:In this paper, the heat generation characteristics of quantum dot system are studied by using the nonequilibrium Green function method, which can provide a model reference and theoretical basis for the design of quantum devices with excellent performance. In the first chapter, the basic knowledge of mesoscopic systems and quantum dots and the method of non-equilibrium Green's function are introduced, and the background and significance of the research on the heat generation properties of quantum dots are also described. In chapter 2, the thermal properties of quantum dots coupled with ferromagnetic electrode are studied. It is found that when the magnetic moment direction of two electrodes is parallel to each other, the total heat is independent of the spin-polarizability of the electrode, and when the magnetic moment direction of the two electrodes is opposite to each other, The effect of ferromagnetism on heat generation is different from that on current. Under weak Coulomb action and low bias voltage, the intensity of heat generation decreases monotonously with the increase of the magnetic susceptibility of the electrode, whereas the heat generation and the spin-polarizability of the electrode show a non-monotone relationship due to the effect of spin accumulation. In the third chapter, the thermal properties of quantum dot systems with ferromagnets and metal electrodes are investigated. It is found that under the influence of Coulomb blocking effect, the current varies non-monotonously in the whole bias voltage range. When the spin polarizability of ferromagnetic electrode is constant, the heat flux and current polarizability at positive bias are higher than those at negative bias, respectively. In chapter 4, the thermal properties of quantum dots coupled with noncollinear ferromagnetic electrodes are investigated. It is found that the angle between the magnetic moments of the two electrodes varies from 0 to 0 for the intensity of heat generation. No reference source was found. In the process of increasing monotonously, the current decreases continuously. The intensity of heat generation has different dependence on the spin-polarizability of the electrode at different magnetic moment angles. When the magnetic moment of the two electrodes is noncollinear and one electrode is semi-metallic, the heat generation property is more sensitive to the spin polarization intensity. Chapter five gives the conclusion of this paper.
【学位授予单位】：渤海大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O471.1

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