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

除了电荷之外，电子还具有内在的自旋，它会产生像微型条形磁铁一样的磁矩。自旋电子学，即操纵和控制电子自旋的技术应用，已经导致了技术突破，例如今天广泛用于硬盘驱动器的磁存储器。在纳米尺度上实现更大的能力来利用自旋相关现象，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所谓的电荷自旋轨道耦合（SOC）来操纵自旋，SOC将电子的空间运动与其自旋耦合。这通过利用堆叠在一起的原子级薄的二维材料来实现，以便创建具有不同SOC强度的区域的异质结构材料。例如，虽然石墨烯具有非常低的SOC，但是当堆叠到过渡金属二硫属化物（TMD）材料上时，其SOC变得显著。该研究小组创建了具有可调空间分布，SOC大小和方向的设备，并实现了拓扑超导性，这可能成为量子信息处理的基础。这项研究是与教育和培训的本科生和研究生的下一代量子劳动力的综合课程相结合。技术说明虽然SOC使新的方法来控制纳米结构中的自旋和产生新的拓扑电子基态，它也可以减少自旋寿命。由于二维材料允许可调SOC，它们提供了一个有前途的平台，利用SOC进行自旋操纵，同时实现长的自旋寿命。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的双电子和空间工程的新型自旋电子和拓扑器件。目标包括（1）。使用石墨烯/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操纵以实现自旋谷阀和纯自旋电流的产生;以及（3）. - 通过将石墨烯/TMD异质结构耦合到超导体来实现拓扑超导性，其例如通过改变石墨烯中的费米能而原位可调，并且通过改变扭转角而可工程化。研究项目的成功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模块迈出重要一步。除了培养研究生外，研究团队成员将继续他们在指导本科生和高中生方面的既定努力，以及招募和指导代表性不足的群体。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

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.