Many-Body Effects in Electronic Dynamics and Transport

在过去的二十年里，人们对纳米器件中的电子输运和动力学的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了相互作用效应。这个理论研究项目旨在通过形式的发展和对简单模型的详细分析来提高我们对电子关联(多体效应)在纳米电子中的作用的基本理解。该程序分为三个部分，分别建立在当前活动的不同但相互关联的方面。含时(自旋)电流密度泛函理论(CDFT)的发展和应用。这个理论允许用依赖于时间的耗散有效场来描述多体效应。这一发展将包括将理论扩展到开放系统(以便研究输运)；证明非共线自旋动力学有效场的唯一性定理；构造新的频率相关势；以及对(自旋)带隙问题的新攻击。这些应用将从求解耦合量子点系统在非均匀含时磁场中的自旋动力学开始(重点是磁化反转时间和Gilbert衰减的出现)，然后继续分析这些系统中与自旋相关的输运。自旋输运中的关联效应。在这一领域将开展几个项目，包括“自旋质量”的理论和计算(在玻尔兹曼方程方法中计算自旋流的关键)；存在自旋-阻力摩擦时的弱场和高场自旋注入理论；在一维通道相互作用的Landauer-Buttiker(LB)形式中包含自旋-阻力效应；存在Rashba自旋-轨道耦合的二维电子液体的多体理论。自旋-电子器件的理论分析。分析了一种新型自旋晶体管的输运特性，该晶体管由两个由窄收缩连接的宽铁磁区组成。平坦-维格纳莱单极自旋晶体管概念的这种变化具有的优点是，可以使两个区域之间的磁畴壁的厚度非常小，从而获得效率上的增益。我们将介绍和求解非共线自旋积累的漂移扩散方程。在过去的二十年里，人们对纳米器件中的电子输运和动力学的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了相互作用效应。这个理论研究项目旨在通过形式的发展和对简单模型的详细分析来提高我们对电子关联(多体效应)在纳米电子中的作用的基本理解。该计划分为三个部分，以当前活动的不同但相互关联的方面为基础。

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.***