Many-Body Effects in Electronic Dynamics and Transport

在过去的二十年里，人们对纳米尺度器件中的电子输运和动力学研究产生了极大的兴趣。 大多数理论工作通常是在单电子描述中进行的，通过静态自洽势考虑相互作用效应。 该理论研究计划旨在通过正式的发展和对简单模型的详细分析，提高我们对纳米电子学中电子相关性（多体效应）作用的基本理解。 该计划分为三个部分，建立在当前活动的不同但相互关联的方面。时间相关（自旋）-电流密度泛函理论（CDFT）的发展和应用。 这个理论允许描述的多体效应的时间依赖性耗散有效场。 发展将包括扩展的理论开放系统（以便运输可以研究）;证明一个唯一性定理的有效领域的非共线自旋动力学;建设新的频率相关的潜力;和，一个新的攻击（自旋）带隙问题。 应用将开始与自旋动力学在耦合量子点系统中的非均匀的时间相关的磁场的存在下的解决方案（重点是磁化反转时间和出现的吉尔伯特阻尼），并继续与自旋相关的输运在这些系统中的分析。自旋输运中的相关效应。 在这一领域，将进行几个项目，包括理论和计算的“自旋质量”（对玻尔兹曼方程方法中自旋流的计算至关重要）;存在自旋拖曳摩擦时的弱场和高场自旋注入理论;在相互作用的一维通道的Landauer-Buttiker（LB）形式主义中纳入自旋拖曳效应; Rashba自旋轨道耦合下二维电子液体的多体理论。自旋电子器件的理论分析。 本文分析了一种由两个宽铁磁区通过窄收缩连接而成的新型自旋晶体管的输运特性。 Flatte-Vignale单极自旋晶体管概念的这种变化具有这样的优点，即两个区域之间的磁畴壁的厚度可以做得非常小，从而提高效率。 将介绍并求解非共线自旋累积的漂移扩散方程。在过去的二十年里，人们对纳米尺度器件中的电子输运和动力学研究产生了极大的兴趣。 大多数理论工作通常是在单电子描述中进行的，通过静态自洽势考虑相互作用效应。 该理论研究计划旨在通过正式的发展和对简单模型的详细分析，提高我们对纳米电子学中电子相关性（多体效应）作用的基本理解。 该计划分为三个部分，建立在当前活动的不同但相互关联的方面。

The past two decades have witnessed an explosion of interest in the study of electronic transport and dynamics in nano-scale devices. Most theoretical work is usually carried out within a one-electron description, with interaction effects taken into account via static self-consistent potentials. This theoretical research program aims at improving our basic understanding of the role of electron correlations (many-body effects) in nano-electronics through formal developments and a detailed analysis of simple models. The program is organized in three parts which build on different but interrelated aspects of current activities.Development and applications of the time-dependent (spin)-current density functional theory (CDFT). This theory allows a description of many-body effects in terms of time-dependent dissipative effective fields. The development will include extension of the theory to open systems (so that transport can be studied); proof of a uniqueness theorem for the effective fields for non-collinear spin dynamics; construction of new frequency-dependent potentials; and, a new attack to the (spin) band-gap problem. The applications will begin with the solution of the spin dynamics in coupled quantum-dot systems in the presence of non-uniform time-dependent magnetic fields (with emphasis on magnetization reversal times and the emergence of Gilbert damping) and continue with the analysis of spin-dependent transport in these systems.Correlation effects in spin transport. In this area several projects will be undertaken including theory and calculation of the "spin mass" (crucial to the calculation of the spin-current in the Boltzmann equation approach); theory of weak-and high-field spin injection in the presence of spin-drag friction; inclusion of spin-drag effects in the Landauer-Buttiker (LB) formalism for interacting one-dimensional channels; many-body theory of the two-dimensional electron liquid in the presence of Rashba spin-orbit coupling.Theoretical analysis of spin-electronic devices. The transport characteristics of a new spin transistor consisting of two wide ferromagnetic regions connected by a narrow constriction will be analyzed. This variation on the Flatte-Vignale unipolar spin transistor concept has the advantage that the thickness of the magnetic domain wall between the two regions can be made very small, with consequent gain in efficiency. Drift-diffusion equations for non-collinear spin accumulations will be introduced and solved.%%%The past two decades have witnessed an explosion of interest in the study of electronic transport and dynamics in nano-scale devices. Most theoretical work is usually carried out within a one-electron description, with interaction effects taken into account via static self-consistent potentials. This theoretical research program aims at improving our basic understanding of the role of electron correlations (many-body effects) in nano-electronics through formal developments and a detailed analysis of simple models. The program is organized in three parts which build on different but interrelated aspects of current activities.***