Project title: Discovering Twisted Bilayer Materials with Strong Electron Correlations
Supervisors: Johannes Lischner and Arash Mostofi
Twisted bilayer graphene (tBLG) has been studied theoretically for over a decade, but the recent experimental observation of insulating behaviour and unconventional superconductivity has triggered renewed interest in this system. tBLG promises novel insights into strongly correlated materials, such as the high-transition-temperature superconducting cuprates, as the strength of electron correlations can be systematically tuned via the twist angle and doping can be controlled by an external electric field. In this project, we aim to develop low-energy effective Hamiltonians of tBLG, free of empirical parameters, which will be used to predict properties of tBLG accurately and provide insights into the nature of the experimentally-observed electronic phases.
We will also search for signatures of strongly-correlated physics in other twisted bilayer systems that could be made from the many thousands of 2D materials that are predicted to be stable. Exploration of the large space of possible bilayer systems necessitates the development of automated high-throughput workflows to calculate their electronic properties. These workflows will seamlessly parametrise efficient tight-binding models for simulating large bilayer systems with small twist angles (which are more likely to exhibit strongly-correlated behaviour) using first-principles calculations of smaller bilayer systems with larger twist angles.