Twistronic and spatial modulation of spin orbit coupling for spintronic and topological devices

除了电荷，电子还具有一种固有的自旋，这种自旋产生的磁矩就像一个微小的条形磁铁。自旋电子学，即为技术应用操纵和控制电子自旋，导致了技术突破，例如今天在硬盘驱动器中广泛使用的磁存储器。在纳米尺度上获得更大的利用自旋相关现象的能力，有望开发用于数据存储和信息处理的新型设备。该研究项目旨在通过控制电荷的自旋-轨道耦合（SOC）来操纵自旋，该耦合将电子的空间运动与自旋耦合在一起。这是通过利用原子薄的二维材料堆叠在一起来实现的，从而创建具有不同SOC强度区域的异质结构材料。例如，虽然石墨烯具有非常低的SOC，但当堆叠在过渡金属二硫化物（TMD）材料上时，其SOC就变得非常重要。研究小组创造了具有可调SOC空间分布、大小和方向的器件，并实现了拓扑超导性，这可能成为量子信息处理的基础。这项研究与下一代量子劳动力的本科和研究生教育和培训的综合课程相结合。技术描述虽然SOC使控制纳米结构中的自旋和产生新的拓扑电子基态的新方法成为可能，但它也可以减少自旋寿命。由于二维材料允许可调的SOC，它们为利用SOC进行自旋操作提供了一个有前途的平台，同时实现了较长的自旋寿命。该研究项目建立在团队先前在制造高迁移率石墨烯/TMD异质结构方面的工作和专业知识的基础上，旨在开发基于SOC的涡旋电子和空间工程的新型自旋电子和拓扑器件。目标包括(1)。利用石墨烯/TMD层间扭转角和费米能级调谐来控制SOC的大小和类型（Rashba vs. Ising）；（2）. 空间SOC操纵实现自旋谷阀和产生纯自旋电流；(3)通过将石墨烯/TMD异质结构耦合到超导体上实现拓扑超导，这可以通过改变石墨烯中的费米能量来原位调节，也可以通过改变扭转角来实现工程化。成功的研究项目实施将导致在没有磁性材料或磁场的情况下操纵自旋，并朝着开发容错量子计算的构建块迈出了重要的一步。除了培训研究生外，研究小组成员还将继续努力指导本科生和高中生，并招募和指导代表性不足的群体。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical descriptionIn addition to charge, electrons also possess an intrinsic spin that produces a magnetic moment like a tiny bar magnet. Spintronics, i.e. manipulation and control of electron spin for technological applications, has led to technological breakthroughs such as the magnetic memory that is widely used in hard drives today. Achieving yet greater ability to harness spin-related phenomena in the nanoscale promises the development of novel devices for data storage and information processing. This research project aims at manipulating spin via controlling so-called spin-orbit coupling (SOC) of charges, which couples the spatial motion of the electron to its spin. This is achieved by taking advantage of atomically thin two-dimensional materials that are stacked together, so as to create heterostructure materials with regions of different SOC strengths. For example, while graphene has very low SOC, when stacked onto transition metal dichalcogenide (TMD) materials its SOC becomes significant. The research team creates devices with tunable spatial distribution, magnitude and direction of SOC, and realizes topological superconductivity that could potentially form a basis for quantum information processing. This research is integrated with a comprehensive course of education and training of undergraduate and graduate students for the next generation of the quantum workforce.Technical descriptionWhile SOC enables new ways to control spin in nanostructures and produce new topological electronic ground states, it can also reduce spin lifetimes. As two-dimensional materials allow tunable SOC, they provide a promising platform to harness SOC for spin manipulation while enabling long spin lifetime. This research project builds on the team’s prior works and expertise in fabricating high mobility graphene/TMD heterostructures and aims to develop new classes of spintronic and topological devices based on twistronic and spatial engineering of SOC. Goals include (1). Using graphene/TMD interlayer twist angle and Fermi level tuning to control the magnitude and type of SOC (Rashba vs. Ising); (2). Spatial SOC manipulation to achieve spin-valley valves and generation of pure spin currents; and (3). realizing topological superconductivity by coupling graphene/TMD heterostructures to superconductors, which is tunable in situ for example by varying the Fermi energy in graphene and engineerable by varying the twist angle. Successful research project implementation will lead to the manipulation of spins without magnetic materials or magnetic fields and a major step towards developing building blocks for fault-tolerant quantum computation. In addition to training graduate students, the research team members will continue their established efforts at mentoring undergraduate and high school students in addition to recruiting and mentoring underrepresented groups.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.