Theory & Simulation of Twisted Bilayer Materials

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Recently, twisted bilayers of two-dimensional (2D) materials have emerged as a new platform for studying the properties of strongly-correlated electrons. In these systems, two sheets of 2D materials are stacked on top of each other with a twist angle, resulting in a Moiré pattern with a periodicity that has a length-scale that can be orders of magnitude larger than that of the underlying atomic lattices. The Moire' pattern induces a superlattice potential which reduces the kinetic energy of electrons and results in the emergence of correlation-induced phenomena absent in the individual layers, such as magnetism, insulating behaviour or even unconventional superconductivity. Whilst twisted bilayer graphene is the most intensely studied twisted bilayer system due to the experimental discovery of superconductivity upon doping the correlated insulator state at certain "magic" twist angles, there is a large space of promising twisted bilayer systems that can be formed by stacking other 2D materials such as transition metal dichalcogenides (TMDCs) and hexagonal boron nitride (h-BN). The properties of such systems remain largely unexplored. In this project, we will use theory and simulation (including tight-binding and many-body methods) to investigate the electronic and optical properties of candidate twisted bilayer systems involving TMDCs, h-BN and graphene and attempt to unravel the nature of superconductivity in these systems.