Correlated states in graphene heterostructures

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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.