SPIN ELECTRONICS: Interplay Between Spin Transport and Magnetization Dynamics in Magnetic Nanostructures

这项提案是为了响应21世纪的自旋电子学倡议，计划征集NSF 02-036而收到的。该方案着重于电流驱动的磁化动力学和磁性纳米结构中自旋输运的磁组态依赖之间的相互作用，即给出大电流作用下磁性纳米结构的磁性和输运性质的整体方法。对于包括多层柱状结构和磁性纳米收缩在内的几种磁性纳米结构，通过求解广义Boltzmann方程，可以得到非共线磁化构型的自旋累积和自旋流。通过微磁学程序求解Landau-Lifshitz-Gilbert方程，研究了存在自旋积累和自旋流时的磁化动力学。由于自旋积累和磁化动力学是相互依赖的，非平衡电子分布的运动方程和局域磁化强度的运动方程必须自洽地确定。在整个研究项目中，将对程序中开发的模型和最新的(现有的和正在进行的)自旋电流感应磁化动力学的实验数据进行广泛的比较。该项目要求将自旋电子器件的基础研究和应用理论很好地结合起来。这项研究的结果将为理解传导电子非平衡状态下磁性纳米收缩的磁化动力学提供一个一般的理论框架。本研究开发的数值模拟工具很可能广泛用于实验人员和工程师解释、预测和设计高速、高密度自旋电子学和其他纳米级器件。我们预计，通过研究生和博士后的参与，以及通过与产业界的合作，该项目将产生广泛的影响。这些研究成果将被整合到国际磁学研究所打算开发的一门新兴的磁性和磁性材料前沿课程中。

This proposal was received in response to the Spin Electronics for the 21st century Initiative, Program Solicitation NSF 02-036. The proposal focuses on the interplay between current-driven magnetization dynamics and the magnetic configurational dependence of spin transport in magnetic nanostructures, i.e., to give a holistic approach to the magnetic and transport properties of magnetic nanostructures subject to a high current flow. Spin accumulation and spin current of non-collinear magnetization configuration will be obtained by solving the generalized Boltzmann equation for several magnetic nanostructures, including the multilayered pillar structure and the magnetic nanoconstriction. Magnetization dynamics in the presence of the spin accumulation and spin currents will be investigated by solving Landau-Lifshitz-Gilbert equation through micromagnetics codes. Since the spin accumulation and the magnetization dynamics are inter-dependent, the equations of motion for the non-equilibrium electron distribution and for the local magnetization must be self-consistently determined. An extensive comparison between the models developed in the program and updated (available and on-going) experimental data on spin-current induced magnetization dynamics will be given throughout this research project. The project calls for a well-balanced combination of fundamental studies and applications of the theory for spintronics devices. The outcome of the proposed research will be a general theoretical framework for understanding the magnetization dynamics of magnetic nanoconstrictions in a non-equilibrium state of conduction electrons. It is likely that the numerical modeling tools developed in this research can be widely used for experimentalists and engineers to explain, predict, and design for high-speed, high-density spintronics and other nanoscale devices. We anticipate a broad impact from this program through participation of a graduate student and a post-doc, and through partnership with industry. The research results will be integrated into an emerging course of the frontier of magnetism and magnetic materials that the PI intends to develop.