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

该提案是响应21世纪世纪自旋电子学倡议，计划征集NSF 02-036而收到的。该提案的重点是电流驱动的磁化动力学和磁性纳米结构中自旋输运的磁性构型依赖性之间的相互作用，即，给出了一个整体的方法，磁性纳米结构的磁性和输运性能受到高电流。通过求解几种磁性纳米结构的广义Boltzmann方程，得到了非共线磁化结构的自旋积累和自旋电流，包括多层柱状结构和磁性纳米收缩结构。通过微磁学程序求解Landau-Lifshitz-吉尔伯特方程，研究了自旋积累和自旋电流存在下的磁化动力学。由于自旋积累和磁化动力学是相互依赖的，非平衡电子分布和局部磁化的运动方程必须自洽确定。在整个研究项目中，将给出在程序中开发的模型和更新的（可用的和正在进行的）自旋电流感生磁化动力学实验数据之间的广泛比较。该项目要求自旋电子学器件的基础研究和理论应用的平衡结合。所提出的研究结果将是一个一般的理论框架，用于理解在非平衡态的传导电子的磁性纳米收缩的磁化动力学。在这项研究中开发的数值模拟工具很可能可以广泛用于实验学家和工程师解释，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，并通过与业界的合作伙伴关系，从这个计划的广泛影响。研究成果将被整合到PI打算开发的磁性和磁性材料前沿的新兴课程中。

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.