Collaborative Research: Investigation of Correlated Many-body Physics in Multilayer Semiconducting Moire Superlattices

Non-technical Abstract Understanding how electrons interact with each other in materials is one of the most exciting and challenging areas of modern physics. When these interactions become strong, they can lead to unusual and fascinating states of matter that can enable future technology revolution, such as materials that conduct electricity without resistance or those that could form the basis of future quantum technologies. However, these so-called correlated states are challenging to study due to their complex, many-body nature. This project focuses on exploring these correlated states in a new class of materials made from stacking atomically thin semiconducting layers with a slight twist or mismatch, creating a new periodic "moiré superlattice". This structure can slow down electrons and enhance their interactions, making it possible to observe and control new quantum states. The research team brings together experts in building these delicate materials, shining light on them to understand their optical properties, and using sensitive microscopes to probe their electrical behavior at the nanoscale. The project will explore how different ways of stacking the layers and controlling electron flows can create entirely new states of quantum matter. This project aligns with the goals of the National Quantum Initiative and has the potential to drive innovation in quantum electronics and optoelectronics. Beyond the science, this project will help train the next generation of scientists and engineers in fields of quantum optics, optoelectronics, and nanotechnology. The team will involve students ranging from high school to graduate school, with a strong focus on outreach activities. Activities will also include lab tours, educational modules, and hands-on research experiences, helping to grow and prepare the future quantum workforce. Technical abstract Recent advances in moiré superlattices of graphene and transition metal dichalcogenide (TMD) have demonstrated a promising platform to investigate correlated physics in two dimensions. This project aims to investigate correlated quantum phases in multilayer TMD moiré superlattices, leveraging state-of-the-art techniques in device fabrication, optical spectroscopy, and electrical scanning probe microscopy. The proposal focuses on three major research directions: (1) Study the evolution of excitonic insulator state in moiré superlattices involving a natural bilayer; (2) Explore emerging correlated states enabled by tuning interlayer coupling between moiré and non-moiré states. (3) Investigate correlated states in two coupled moiré superlattices. By controlling the electron tunneling from correlated electrons to designed bands, including moiré flatbands, this proposal plans to systematically explore new quantum correlated states and their unique valley/spin physics. 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.