DMREF: Collaborative Research: The Search for Novel Superconductors in Moire Flat Bands

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Non-technical Description: This project will investigate novel unconventional superconductors based on atomically thin materials stacked with a twisted angle between them. When two atomic layers with similar atomic structure meet each other, a larger scale quasi periodic structure called a moire pattern forms. Electronic structure of these interfacial structure can be engineered by adjusting the twisting angle. When the electron energy distribution is narrow, strong correlation between them appear, which can in turn drive the system to be a dissipationless superconducting state. Experimental and theoretical research, in conjunction with the predictive powers of advanced computational methods, will be developed to achieve a better understanding of the physical mechanisms at work and will contribute to the ability to design superconducting materials with higher transition temperatures. The project will provide fundamental understanding of the materials properties and phenomena that underpin superconducting electronic device applications in low energy electronics, quantum sensing, and more importantly quantum computing applications. A new generation of scientists will be trained who are deeply involved in both experimental and theoretical/modeling research with complimentary expertise.Technical Description: The moire heterostructure engineering of 2-dimensional (2D) van der Waals (vdW) materials leads to quantum heterostructures. Utilizing recently demonstrated twisted vdW heteroepitaxy, the investigators will construct vdW homo/hetero structures to realize correlated electronic states that appear in the moire flat bands. With inputs from theory and mathematical modeling of multiscale electronic structure, the project will experimentally investigate multilayer 2D superconducting systems with unusual properties, such as gate tunable transition temperature and non-conventional pairing symmetries. Various material platforms will be explored including twisted double bilayer graphene, twisted trilayer graphene and twisted homo- and hetetro-structures based on transition metal dichalcogenides. Theoretical guidance will be an indispensable part of this study since there are a variety of choices for material platforms and twist angle which cannot be covered by experiment alone without targeted modeling guide. Unconventional superconductivity can also lead into the development and discovery of topological superconductors, which can be utilized for quantum computing. The qubits realized in topological superconducting systems hold promise for fault-tolerant quantum computation, thanks to the topological nature of the underlying quantum states.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.