Collaborative Research: Correlated States in Twisted Hetero-bilayer Transition Metal Dichalcogenides

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Nontechnical Abstract: In conventional materials, electrons travel in the periodic arrays of atoms without "talking" (interacting) to each other. When two monolayers of atomically thin materials, also knowns as two-dimensional (2D) materials, are stacked together with a well-controlled twist angle between these two layers, they form a new periodic structure with interesting properties. In this collaborative project, the PIs investigate these 2D materials to gain knowledge that could enable transformative technology innovations such as high-temperature superconductivity, quantum electronics and optoelectronics. This project integrates an education component to train students and build a strong workforce for quantum science and technologies. Under-represented groups are particularly encouraged and included in the education programs.Technical Abstract: Correlated states such as Mott insulators and Wigner crystals remain intriguing subjects of physics. More recently, twisted hetero-bilayer transition metal dichalcogenides (TMDs) have emerged as a new platform with even more enhanced correlation strength, and their strong spin-orbit coupling and presence of bandgaps provide new avenues to explore spin-related physics and optoelectronics in correlated states. In this collaborative proposal, the PIs explore the moiré superlattices formed by twisted hetero-bilayer TMDs. The research plan includes two main thrusts. Thrust I is to characterize the interaction strength of the correlated states and study its relationship with moiré structure parameters and external controls to manipulate the correlated states. Thrust II is to explore new correlated states arising from interactions with other electronic phases, such as the interplay of correlated states with Landau levels, the effect of strong correlation on valley physics and excitonic physics of the moiré superlattice, and other types of new states that could possibly arise in this strongly interacting system. The collaborative project trains graduate and undergraduate students are trained for future placement in quantum science and technologies. The project also creates research modules for outreach to K-12 students and actively involves under-represented groups.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.