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

该奖项支持磁性纳米结构磁化动力学的计算和理论研究，该研究与本科生教育相结合。本项目旨在促进对纳米级结构的磁态与表面之间相互作用的理解，特别是材料内部缺陷和其他畴壁对畴壁定位的依赖。许多用于记录、传感和逻辑操作的磁性器件已经被提出，其中纳米线中畴壁的运动和控制是必要的操作条件。这些提出的设备大多数都需要在同一结构中存在其他设备的情况下控制单个域壁，这就需要了解发生的重要相互作用。该项目将邀请本科物理专业的学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存在于纳米线中的多个磁畴的控制行为。这项工作采用微磁模拟方法来帮助测试和验证理论，并帮助解释磁畴运动的实验。纳米空间分辨率与同步皮秒时间分辨率的结合，使微磁模拟成为研究磁纳米线场驱动畴壁运动的理想方法。由于纳米线的尺寸较小，在实验上很难对磁纳米线的畴壁运动进行动态观察。研究将产生在其他壁存在的情况下操纵单个域壁而不丢失关键信息的技术。最终，这项工作影响了所提出器件的可行性，并增加了纳米结构材料中磁化动力学的知识基础，而不是块状材料。该奖项支持与本科生教育相结合的计算和理论研究。在这项倡议中，研究和教育的发展是为了推进理论和使用计算机来模拟纳米级记录设备的磁性材料。研究工作集中在理解和推进纳米结构中磁性材料的操作，这需要理解和控制磁性器件，并促进其在高密度和极快磁记录设备中的未来应用。本项目由物理专业本科学生参与，进行计算机仿真和理论建模。学生从研究经验中受益，这一过程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用于导论课程的当前主题，以突出经典物理学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器件中产生的单个磁性区域。这些区域的运动正在通过实验和理论研究，因为它们在极快和小的磁存储和传感应用中有潜在的应用。该项目采用计算机模拟方法来帮助测试和验证理论，并帮助解释磁区运动的实验。计算机模拟是唯一能在如此小的结构中同时获得空间和时间的技术。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。磁性纳米器件中磁区位置和运动的可靠控制对未来几代磁性硬盘驱动器以及逻辑器件至关重要。操纵运动可以产生可变磁场传感器，这取决于磁畴的位置或磁畴的数量。

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.