Quantum Transport in Twisted Van Der Waals Heterostructures

非技术摘要范德华材料类似于一副分层的纸牌：它们是由与邻居粘合较弱的单个纸片制成的。在过去的十年里，人们发现这些单独的薄片可以被剥离，以产生一原子厚的材料。这一非常令人惊讶的发现首先是用石墨来分离被称为石墨烯的单原子层。从那时起，这项技术已经被应用于一系列材料，以分离出新形式的二维层状晶体。当以这种方式隔离时，已经发现薄的层状片具有新的性质，这可以用于广泛的电子应用。在这项研究的前沿是范德华异质结构的创造，这是通过结合不同材料的薄层来创建具有新颖功能的全新结构。这项研究项目探索了如何通过扭曲结构来改变组合结构的性质，即通过改变相邻堆叠层之间的旋转对齐。一层相对于另一层的扭曲会极大地影响两层之间的耦合，导致组合结构的电子性质大不相同。通过这种方式，新的电子材料的性质可以被调节以用于不同的目的，例如用于研究奇异的量子现象，或者获得具有新的电子和光学性质的新型量子纳米器件。该项目将作为一个广泛整合的计划的一部分完成，该计划旨在建立一个合作和开放的科学社区，指导下一代科学家，并向行业领导者和普通公众交流物理学。技术摘要堆积2D晶层以形成van der Waals异质结构成了创造设计型电子材料的新范例。由于层间耦合和库仑相互作用对层间旋转排列或扭转角度的敏感性，可能的电子现象的范围特别丰富。这个项目的研究目标是了解决定扭曲范德华异质结构性质的层间物理，并在此基础上设计出新的量子电路。拟议的研究目标将通过纳米制造和输运测量来实现，范德华异质结构是由原子薄层石墨烯和六方氮化硼堆积而成的。这个项目的成功将有助于理解由于层间耦合和电子-电子相互作用而导致的范德华异质结构中相互作用的影响。此外，电子-电子相互作用有望产生新的高关联基态和新的边态组态，如分数量子自旋霍尔效应。本项目将探索扭曲范德华异质结构中的这些新颖的多体状态，并探索它们实现未来拓扑保护量子电路的构建块的潜力。这项研究还可能导致新的量子相干电子器件，并将在评估范德华异质结构成为未来纳米电子学和量子信息技术中的一个组件的潜力方面具有重要意义。

Non-Technical AbstractVan der Waals materials resemble a layered deck of cards: they are made of individual sheets which are weakly bonded to their neighbors. In this last decade it was discovered that these individual sheets can be peeled off to produce a one-atom thick material. This highly surprising discovery was first made with graphite to isolate single atomic layers called graphene. Since then this technique has been applied to a range of materials to isolate new forms of 2-dimensional layered crystals. When isolated in this way, it has been found that the thin layered sheets take on new properties which can be useful for a wide range of electronics applications. At the forefront of this research is the creation of van der Waals heterostructures, which are made by combining thin layers from different materials to create entirely new structures with novel functionality. This research project explores how the properties of the combined structure can be altered by "twisting" the structure, i.e. by changing the rotational alignment between adjacently stacked layers. Twisting one layer with respect to another can drastically affect the coupling between the two layers, resulting in widely different electronic properties for the combined structure. In this way the properties of the new electronic material can be tuned for different purposes such as for the study of exotic quantum phenomena or to obtain novel quantum nanodevices with new electronic and optical properties. This project will be accomplished as part of a broadly integrated program aimed at building a collaborative and open scientific community, mentoring the next generation of scientists, and communicating physics to industry leaders and the general public. Technical AbstractThe stacking of 2d crystalline layers to form van der Waals heterostructures constitutes a new paradigm for creating designer electronic materials. The range of possible electronic phenomena is especially rich due to the sensitivity of interlayer coupling and Coulomb interactions to the rotational alignment between layers, or twist angle. The research objective of this project is to understand the interlayer physics that determine the properties of twisted van der Waals heterostructures and to build upon this understanding to engineer novel quantum circuits. The proposed research objective will be achieved through the nanofabrication and transport measurement of van der Waals heterostructures made from stacking atomically-thin layers of graphene and hexagonal boron nitride. The success of this project will result in an understanding of the effect of interactions within van der Waals heterostructures due to interlayer coupling and electron-electron interactions. Moreover, electron-electron interactions are expected to give rise to new highly-correlated ground states and novel edge state configurations such as the fractional quantum spin Hall effect. This project will probe these novel many-body states in twisted van der Waals heterostructures and explore their potential for realizing building blocks for future topological-protected quantum circuits. This research may also result in new quantum coherent electronic devices, and will be of importance in assessing the potential of van der Waals heterostructures to become a component in future nanoelectronics and quantum information technologies.