Controlling Multiple Domain Walls in Ferromagnetic Nanowires with Magnetic Fields Studies by Micromagnetic Simulation

技术总结该奖项支持与本科生教育相结合的磁性纳米结构中磁化动力学的计算和理论研究。该项目旨在促进对磁性状态和纳米结构表面之间的相互作用的理解，特别是由于缺陷和材料内其他磁场壁而导致的磁场壁位置的依赖关系。已经提出了许多用于记录、传感和逻辑操作的磁性设备，其中纳米线中的磁场壁的运动和控制是必要的操作条件。这些被提议的设备中的大多数需要在同一结构中的其他人在场的情况下控制单独的域壁，这就需要了解发生的重要相互作用。该项目将邀请物理学专业的本科生参与进行计算机模拟。学生将从研究经验中受益，并在此过程中，增加他们在磁性材料和纳米技术方面的教育。新的理论和计算机模拟将被用来理解和预测纳米线中存在的多个磁畴的控制行为。这项工作使用微磁模拟方法来帮助测试和验证理论，并帮助解释关于磁畴运动的实验。纳米空间分辨率和皮秒时间分辨率的结合使得微磁模拟成为研究磁性纳米线中场驱动磁区壁面运动的理想方法。由于纳米线的尺寸较小，在实验上很难动态观察磁性纳米线中的磁畴壁运动。调查将产生在不丢失关键信息的情况下在其他墙存在的情况下操纵单个域墙的技术。最终，这项工作影响了所建议的装置的可行性，并增加了关于纳米结构材料而不是块状材料中磁化动力学的知识基础。非技术总结该奖项支持与本科生教育良好结合的计算和理论研究。在这一倡议中，开展了研究和教育，以促进计算机模拟纳米级记录设备的磁性材料的理论和使用。研究工作集中在了解和推进纳米结构中磁性材料的操纵，这些操纵是理解和控制磁性设备所需的，并促进它们未来在高密度和极快的磁记录设备中的应用。该项目邀请物理学专业的本科生参与进行计算机模拟和理论建模。学生从研究经验中受益，在这个过程中，研究经验增加了他们在磁性材料和纳米技术方面的教育。一些较简单的解释和结果被用于入门课程的当前主题，以强调经典物理在现代研究和技术中的重要性。新的理论和计算机模拟被用来理解和可靠地控制可以在纳米设备中产生的各个磁区。这些区域的运动正在被实验和理论研究，因为它在极快和极小的磁存储和传感应用中具有潜在的应用价值。该项目使用计算机模拟方法来帮助测试和验证理论，并帮助解释关于磁区运动的实验。计算机模拟是在如此小的结构中同时访问空间和时间的唯一技术。所提出的模拟结果对于理解如何操纵纳米线中特定磁性区域的位置也很重要，这是开关和逻辑的基础。对磁性纳米器件中磁区位置和运动的可靠控制对于下一代磁性硬盘驱动器以及逻辑器件来说是至关重要的。操纵这一运动可能会产生可变磁场传感器，这取决于磁区的位置或磁区的数量。

TECHNICAL SUMMARYThis award supports computational and theoretical research on magnetization dynamics in magnetic nanostructures that is integrated with undergraduate student education.This project aims to advance the understanding of the interaction between the magnetic state and the surface of nanoscale structures, in particular, the dependence of domain wall positioning due to defects and other domain walls inside the material. Many magnetic devices for recording, sensing, and logic operations have been proposed in which the motion and control of a domain wall in a nanowire is a necessary operating condition. Most of these proposed devices require the control of individual domain walls in the presence of others within the same structure which necessitates the need for understanding the important interactions taking place.The project will engage undergraduate physics majors to participate in carrying out computer simulations. Students will benefit from the research experience, and in the process, add to their education in magnetic materials and nanotechnology.New theories and computer simulations will be employed to understand and predict the behavior for control of the multiple magnetic domains that exist in nanowires. This work employs micromagnetic simulation methods to help test and validate theories and aid in the interpretation of experiments on motion of the magnetic domains. The combination of nanometer spatial resolution with concurrent picosecond temporal resolution makes micromagnetic simulation an ideal method for studying the field driven domain wall motion in a magnetic nanowire. Dynamic observation of domain wall motion in a magnetic nanowire is difficult experimentally due to the small size of nanowires. Investigations will yield techniques to manipulate individual domain walls in the presence of other walls without the loss of critical information. Ultimately this work impacts the viability of the proposed devices and increases the base of knowledge about magnetization dynamics in nanostructured materials as opposed to bulk materials.NONTECHNICAL SUMMARYThis award supports computational and theoretical research that is well integrated with undergraduate student education. In this initiative research and education are developed to advance the theory of and the use of computers to simulate magnetic materials for nanoscale recording devices. Research efforts concentrate on understanding and advancing the manipulation of magnetic materials in nanostructures that are needed to understand and control magnetic devices and to promote their future use in high density and extremely fast magnetic recording devices.The project engages undergraduate physics majors to participate in carrying out the computer simulation and theoretical modeling. Students benefit from the research experience which in the process adds to their education in magnetic materials and nanotechnology. Some of the simpler interpretations and results are used for current topics in introductory courses to highlight the importance of classical physics in modern research and technology.New theories and computer simulations are employed to understand and reliably control the individual magnetic regions that can be created in nanodevices. The motion of these regions is being investigated by experiments and theories because of the potential application in extremely fast and small magnetic storage and sensing applications. This project employs computer simulation methods to help test and validate theories and aid in the interpretation of experiments on motion of the magnetic regions. Computer simulation is the only technique which gives simultaneous access to space and time in such small structures.The results of the proposed simulations are also important to understanding how to manipulate the location of a particular magnetic region in the nanowire which is then the basis for switching and logic. Reliable control of the magnetic region location and motion in magnetic nanodevices is essential to future generations of magnetic hard drives, as well as the logic devices. Manipulating the motion could lead to the creation of variable magnetic field sensors which depend on the magnetic domain location or number of domains.