Many-Body Effects in Electronic Dynamics and Transport

在过去的二十年里，人们对纳米级器件中的电子输运和动力学的研究兴趣激增。大多数理论工作通常在单电子描述中进行，通过静态自洽势考虑相互作用效应。本理论研究计划旨在通过正式发展和简单模型的详细分析，提高我们对电子相关（多体效应）在纳米电子学中的作用的基本理解。该方案分为三个部分，以当前活动的不同但相互关联的方面为基础。时变（自旋）电流密度泛函理论的发展与应用。这个理论允许用随时间的耗散有效场来描述多体效应。发展将包括将理论扩展到开放系统（以便可以研究运输）；非共线自旋动力学有效场唯一性定理的证明新的频率相关电位的构建；同时，对（自旋）带隙问题提出了新的解决方法。应用将从求解耦合量子点系统在非均匀时相关磁场下的自旋动力学开始（重点是磁化反转时间和吉尔伯特阻尼的出现），并继续分析这些系统中的自旋相关输运。自旋输运中的相关效应。在这一领域将进行几个项目，包括“自旋质量”的理论和计算（对于波尔兹曼方程方法中自旋电流的计算至关重要）；存在自旋-阻力摩擦的弱场和高场自旋注入理论在相互作用一维通道的Landauer-Buttiker （LB）形式中包含自旋-阻力效应；二维电子液体在Rashba自旋轨道耦合下的多体理论。自旋电子器件的理论分析。本文分析了一种新型自旋晶体管的输运特性。在Flatte-Vignale单极自旋晶体管概念上的这种变化的优点是，两个区域之间的磁畴壁厚度可以做得非常小，从而提高效率。介绍并求解非共线自旋积累的漂移扩散方程。在过去的二十年里，人们对纳米级器件中的电子输运和动力学的研究兴趣激增。大多数理论工作通常在单电子描述中进行，通过静态自洽势考虑相互作用效应。本理论研究计划旨在通过正式发展和简单模型的详细分析，提高我们对电子相关（多体效应）在纳米电子学中的作用的基本理解。该计划分为三个部分，这些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.***