Electric Field Control of Spin Dynamics in Metal Spintronic Devices

该计划的目标是实现电场对新型金属自旋电子器件结构中磁态的控制。这种方法利用了新的和基本上未开发的磁电效应在金属铁磁薄膜。实验集中在材料和异质结构中的磁性行为是由破坏对称性的表面或界面。强电场将用于诱导自旋相关表面电荷层，以影响表面电子结构并调制表面和界面处的关键磁性参数（磁各向异性、磁化、自旋极化和自旋输运特性）。该计划将（1）通过系统的实验数据集提供基本的见解，使电场操纵表面磁性和自旋输运的机制，（2）检查电场可以激发和控制自旋动力学和大角度磁开关的特定模型设备。这项工作解决了在先进的基于自旋的电子学中对有效操作模式的迫切需求，并避免了现有方法的关键限制。如果成功，这些基础研究将实现革命性的新存储器和逻辑器件功能，以超低功耗要求提供增强的性能和耐用性。建议的研究提供了一个平台，并将紧密结合在本科和研究生水平的教育发展，以及通过当地高中教师的参与。智力优点：建议的研究解决纳米磁学和自旋电子学的关键基础问题。电子自旋自由度的电操纵是当今纳米科学研究的前沿领域之一。该计划探索了电操纵磁性状态的新方法，并将对界面电子结构在磁性材料行为中的作用提供关键的基本见解。选择材料系统使得关键参数（即，能带级填充）可以在模型系统中与新的异质结构一起被连续地调谐，在新的异质结构中，可以预见到新颖的和迄今为止未观察到的电场效应。几何约束的微米和纳米结构将制造和实验特点，并通过广泛的微磁模拟，以了解如何控制调制的磁表面各向异性可以用来驱动磁化动力学和磁开关的自旋配置，如磁涡旋和磁畴walls.Broader影响：如果成功，拟议的基础研究可能会带来广泛的技术影响，新的类？自旋电子学用于超低功耗、高性能计算和大容量数据存储的设备，对移动的计算和全球能源效率产生重大影响。该研究将培养纳米技术关键领域的本科生和研究生，包括先进的薄膜生长和表征，纳米纤维和自旋电子学。该计划将支持早期职业PI与德国哈勒马克斯普朗克研究所同事之间的国际合作，并将为支持的研究生提供国际科学培训和经验。该计划通过麻省理工学院本科生研究机会计划，并通过开发课程材料和教学实验室模块，将本科生与研究生合作，将研究和教育结合起来。PI将利用麻省理工学院的外展基础设施？美国材料科学与工程中心（CMSE）和NSF MRSEC，通过NSF-RET计划接待高中教师，通过CMSE社区学院计划接待当地代表性不足的社区学院学生。

The objective of the proposed program is to realize electric field control of the magnetic state in novel metal spintronic device structures. The approach exploits new and largely unexplored magnetoelectric effects in ultrathin metallic ferromagnetic films. Experiments focus on materials and heterostructures in which the magnetic behavior is dictated by broken symmetries at the surface or interface. Strong electric fields will be used to induce spin-dependent surface charge layers to influence the surface electronic structure and modulate key magnetic parameters (magnetic anisotropy, magnetization, spin polarization and spin-transport characteristics) at surfaces and interfaces. The program will (1) provide fundamental insight, via a systematic experimental dataset, of the mechanisms enabling electric field manipulation of surface magnetism and spin transport and (2) examine specific model devices in which electric fields can excite and control spin dynamics and large-angle magnetic switching. The work addresses the pressing need for efficient modes of operation in advanced spin-based electronics, and avoids key limitations in existing approaches. If successful, these fundamental studies will enable revolutionary new memory and logic device capabilities, offering enhanced performance and durability with ultralow power consumption requirements. The proposed research provides a platform for and will be tightly integrated with educational development at the undergraduate and graduate student level, as well as through involvement of local high school teachers.Intellectual Merit:The proposed research addresses key fundamental issues in nanoscale magnetism and spin-electronics. Electrical manipulation of the electron spin degree of freedom is one of the forefront areas of nanoscience research today. This program explores new means to electrically manipulate the magnetic state, and will give key fundamental insights on the roles of interfacial electronic structure in the behavior of ultrathin (down to single atomic layer) magnetic materials. Materials systems are chosen such that key parameters (i.e., band level filling) can be continuously tuned in model systems, together with new heterostructures in which novel and heretofore unobserved electric field effects are anticipated. Geometrically-constrained micro- and nano-structures will be fabricated and characterized experimentally and through extensive micromagnetic simulations in order to understand how controlled modulation of magnetic surface anisotropy can be used to drive magnetization dynamics and magnetic switching of spin configurations such as magnetic vortices and magnetic domain walls.Broader Impacts:If successful, the proposed fundamental research could have broad technological impacts by bringing about new classes of ?spintronic? devices for ultra low-power, high-performance computation and mass data storage, significantly impacting mobile computing and global energy efficiency. The research will train undergraduate and graduate students in key areas in nanotechnology including advanced thin-film growth and characterization, nanofabrication, and spintronics. The program will support an international collaboration between the early-career PI and colleagues at the Max Planck Institute in Halle, Germany, and will offer international scientific training and experience to the supported graduate student. The program integrates research and education by teaming undergraduates with graduate students through the MIT Undergraduate Research Opportunities Program, and through development of course materials and instructional laboratory modules. The PI will make use of the outreach infrastructure of MIT?s Center for Material Science and Engineering (CMSE), and NSF MRSEC, to host high school teachers through the NSF-RET program, and local underrepresented community college students through the CMSE community college program.