Local magnetic measurements of superconductivity in van der Waals heterostructures

非技术摘要：所谓的货车德瓦耳斯（vdW）材料的不断增长的家族提供了一个通用的平台来发现和探索二维中的新的电子现象，这可能使未来的电子器件取得重大进展。vdW材料在平面内具有强键合，而平面通过弱vdW力保持在一起。这使得有可能通过机械剥离从块状晶体分离单独的片，并通过一次堆叠一个片来构建包含不同vdW材料的异质结构。在异质结构中，可以实现超越单一材料的固有性质的物理性质。本项目的重点是VDW异质结构中的超导性。该团队使用的主要工具是扫描磁探针，一种超导量子干涉装置，它提供了测量vdW异质结构中超导性的磁特征所需的灵敏度。该工具允许团队探索如何通过静电门控来修改vdW材料中的超导状态，调整堆叠层之间的扭曲角，层数，施加的单轴应变以及与磁性层和具有强自旋轨道耦合的层的接近度。最终目标是实现、增强和理解vdW异质结构中的新超导态。该项目培养研究生和本科生在科学和技术领域的重要性，包括材料科学，扫描探针显微镜和纳米科学。此外，该项目还包括一个教育和推广部分，将为K-12学生提供实践科学活动。技术摘要：货车范德华（vdW）材料和异质结构提供了一个多功能的平台，探索和实现非常规的超导性，由于可用于堆叠的层状材料的大型库和一系列可用的调谐参数，可以进一步修改电子性能。vdW器件的极低样品体积对使用电输运之外的常规技术来表征其超导特性提出了挑战。该项目使用通过扫描超导量子干涉装置显微镜实现的局部磁测量来直接探测大范围vdW超导体中超流体的性质。这些测量提供了如何通过静电门控，调整堆叠层之间的扭曲角，层数，施加的单轴应变以及通过接近磁性层和具有强自旋轨道耦合的层来修改超导序的见解。该项目也迈出了第一步，在vdW超导体超导序参量的相敏测量，它可以提供超导配对对称性的明确表征。该奖项反映了NSF的法定使命，并已被认为是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的支持。

Non-technical Abstract: The growing family of so-called van der Waals (vdW) materials offers a versatile platform to discover and explore new electronic phenomena in two dimensions which may enable significant advances in future electronic devices. A vdW material has strong bonding within the plane, while the planes are held together by weak vdW forces. This makes it possible to isolate individual sheets through mechanical exfoliation from a bulk crystal and build heterostructures containing different vdW materials by stacking one sheet at a time. In heterostructures, physical properties going beyond the intrinsic properties of a single material may be realized. This project focuses on superconductivity in vdW heterostructures. The main tool the team uses is a scanning magnetic probe, a superconducting quantum interference device, that offers the sensitivity required to measure the magnetic signatures of superconductivity in vdW heterostructures. This tool allows the team to explore how the superconducting state in a vdW material is modified through electrostatic gating, tuning the twist angle between stacked layers, number of layers, applied uniaxial strain as well as proximity with a magnetic layer and layers that have strong spin-orbit coupling. The ultimate goal is to realize, enhance and understand novel superconducting states in vdW heterostructures. This project trains graduate and undergraduate students in areas of scientific and technological importance including materials science, scanning probe microscopy and nanoscience. In addition, this project includes an education and outreach component that will provide hands-on science activities aimed at K-12 students. Technical Abstract: Van der Waals (vdW) materials and heterostructures offer a versatile platform to explore and realize unconventional superconductivity, due to the large library of layered materials available for stacking and a range of available tuning parameters that can further modify electronic properties. The extremely low sample volume of vdW devices poses a challenge in using conventional techniques beyond electrical transport to characterize their superconducting properties. This project uses local magnetic measurements enabled by scanning superconducting quantum interference device microscopy to directly probe properties of the superfluid in a large range of vdW superconductors. These measurements provide insights in how the superconducting order can be modified through electrostatic gating, tuning the twist angle between stacked layers, the number of layers, applied uniaxial strain as well as through proximity with a magnetic layer and layers that have strong spin-orbit coupling. This project also takes first steps towards phase-sensitive measurements of the superconducting order parameter in vdW superconductors, which can provide unambiguous characterization of the superconducting pairing symmetry.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.