Correlated states in graphene heterostructures

摘要纳米材料中电子自由度的控制对于新现象的出现至关重要。最近，许多原子级薄的材料已经被认识到，从超导体到半导体和绝缘体，每一种材料都具有独特的性能。通过在垂直异质结构中结合这些原子薄材料，有望出现新的电子特性。空间分辨探针为精确测量和控制这些二维材料的电子特性提供了独特的机会。这些探针有能力测量材料的方向和它们之间的相互作用。这些量最终决定了异质结构中可以产生的状态类型。本提案所获得的结果将导致新型电子器件的发展，如晶体管、光电探测器和传感器。该计划将为研究生提供培训，并使来自服务不足群体的本科生能够通过亚利桑那科学、工程和数学学者（ASEMS）计划参与研究，并旨在提高这些学生在STEM专业的保留率。本提案将使用扫描探针显微镜和电输运测量相结合的方法来创建和研究石墨烯异质结构中的新型相关态。此外，该项目将培养纳米科学领域的研究生和本科生。虽然石墨烯是一种拓扑上微不足道的半金属，但还有许多其他二维材料有望表现出更奇特的行为，如超导体和拓扑绝缘体。通过在石墨烯和其他材料之间创建垂直异质结构，将在石墨烯器件中创建独特的状态。具体来说，将制造和研究三种不同类型的器件：(1)石墨烯在六方氮化硼上形成相应的堆叠，从而在石墨烯中打开带隙。(2)在超导体上研究石墨烯的邻近效应和周期性磁场自旋效应。(3)拓扑绝缘体上的石墨烯与重金属过渡金属二硫族化合物增强石墨烯中的自旋轨道相互作用。理解石墨烯中所有这些诱导态的关键是能够在原子尺度上绘制它们的行为，这是扫描探针显微镜和电输运测量相结合所提供的。

Non-technical AbstractThe control of electronic degrees of freedom in nanomaterials is essential for the emergence of new phenomena. Recently, many atomically thin materials have been realized that each offer unique properties ranging from superconductors to semiconductors and insulators. By combining these atomically thin materials in vertical heterostructures, new electronic properties are expected to emerge. Spatially resolved probes offer a unique opportunity for precision measurement and control of the electronic properties of these two dimensional materials. These probes have the ability to measure the orientation of the materials and the interactions between them. These quantities ultimately determine the type of states that can be created in the heterostructures. The results obtained in this proposal will lead to the development of novel electronic devices, such as transistors, photodetectors and sensors. The proposed program will provide training for graduate students as well as enable undergraduate students from underserved groups to participate in research through the Arizona Science, Engineering, and Mathematics Scholars (ASEMS) Program, and will aim to increase the retention of these students in STEM majors. Technical AbstractThis proposal will create and study novel correlated states in graphene heterostructures using a combination of scanning probe microscopy and electrical transport measurements. In addition, this project will train graduate and undergraduate students in the field of nanoscience. While graphene is a topologically trivial semi-metal, there are a wide range of other two-dimensional materials which are expected to exhibit more exotic behavior such as superconductors and topological insulators. By creating vertical heterostructures between graphene and these other materials, unique states will be created in graphene devices. In particular, three different types of devices will be fabricated and studied: (1) graphene on hexagonal boron nitride to create a commensurate stacking and therefore open a band gap in graphene. (2) Graphene on superconductors to study the proximity effect and the effect of a periodic magnetic field from vortices. (3) Graphene on topological insulators and heavy metal transition metal dichalcogenides to enhance the spin-orbit interaction in graphene. The key to an understanding of all these induced states in graphene is the ability to map their behavior on the atomic scale that the combination of scanning probe microscopy and electrical transport measurements will provide.