Exotic many-body physics in van der Waals moiré superlattices
When two layers of graphene are stacked on top of each other with a finite relative angle of rotation, a moiré pattern forms. Most strikingly, at so-called “magic angles”, the largest of which is around 1 degree, the bands around the Fermi surface flatten significantly; this enhances the density of states and the impact of electron-electron interactions. Soon after the experimental discovery in 2018 that this enhancement can induce superconductivity and other, including magnetic, instabilities, it became clear that twisted bilayer graphene is only one example of an engineered van der Waals moiré system with a complex phase diagram akin to other strongly correlated materials.
In this talk, I will provide a brief introduction to the rich and diverse field of moiré superlattices built by stacking and twisting graphene and other van der Waals materials. I will further present recent and ongoing projects – involving a combination of analytics, numerics, machine-learning, and experiment – which explore the exotic quantum many-body phases that can be stabilized in these platforms. More specifically, we will first discuss non-reciprocal superconductivity in twisted trilayer graphene and the consequences for the underlying normal state. Depending on time, I will also describe tunable spin-orbit coupling in a novel moiré heterostructure, vestigial superconducting phases, and how machine-learning might be used to extract microscopic physics from measurements in moiré superlattices.