Electric Field Control of Spin Dynamics in Metal Spintronic Devices

该方案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。该方法在超薄金属铁磁薄膜中利用了新的和很大程度上未被探索的磁电效应。实验集中在材料和异质结构中，其磁性行为是由表面或界面上的破缺对称性决定的。强电场将用于诱导自旋相关的表面电荷层，以影响表面电子结构并调制表面和界面的关键磁参数（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)检查特定的模型设备，其中电场可以激发和控制自旋动力学和大角度磁开关。这项工作解决了在先进的基于自旋的电子设备中对有效操作模式的迫切需求，并避免了现有方法中的关键限制。如果成功，这些基础研究将实现革命性的新内存和逻辑器件功能，提供更高的性能和耐用性以及超低功耗要求。拟议的研究提供了一个平台，并将与本科生和研究生水平的教育发展紧密结合，并通过当地高中教师的参与。智力优势：所提出的研究涉及纳米尺度磁学和自旋电子学的关键基础问题。电子自旋自由度的电子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超薄（低至单原子层）磁性材料行为中的作用提供关键的基本见解。材料系统的选择使得关键参数（即带能级填充）可以在模型系统中连续调谐，以及新的异质结构，其中预期新的和迄今为止未观察到的电场效应。几何约束的微纳米结构将通过实验和广泛的微磁模拟来制造和表征，以了解如何利用磁表面各向异性的可控调制来驱动磁化动力学和自旋构型（如磁涡流和磁畴壁）的磁开关。更广泛的影响：如果成功，提议的基础研究可以带来新的自旋电子？超低功耗、高性能计算和海量数据存储设备，显著影响移动计算和全球能源效率。这项研究将在纳米技术的关键领域培养本科生和研究生，包括先进的薄膜生长和表征、纳米制造和自旋电子学。该计划将支持早期职业PI与德国哈雷马克斯普朗克研究所的同事之间的国际合作，并将为受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将本科生和研究生组成团队，并通过开发课程材料和教学实验室模块，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，并通过CMSE社区大学计划接待当地代表性不足的社区大学生。

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.