Many-Body Effects in Electronic Dynamics and Transport

University Of Missouri-Columbia, Columbia MO

Investigators

Abstract

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. ***