Philip Kim1
Harvard University1
Engineering moire superlattices by twisting and stacking two layers of Van der Waals materials has proved to be an effective way to promote interaction effects and induce exotic phases of matter. After discovering superconductivity and correlated insulators in magic-angle twisted bilayer graphene (MA-TBG), several different two-dimensional materials have been utilized to create two-layer twisted systems and various novel phases. Here, the electronic properties of van der Waals moiré superlattices can further be tuned by adjusting the interlayer coupling or the band structure of constituent layers. In this talk, we will discuss emergent electronic states observed in various twisted multilayer graphene, including twisted double bilayer graphene (TDBG), twisted trilayer graphene (TTG) with alternative twisting angles. We also fabricate <i>n</i>-layer twisted graphene with alternating twisted angle, where $n \geq 4$. In these twisted multilayer graphene systems, we also demonstrate a flat electron band that is tunable by perpendicular electric fields in a range of twist angles. Various correlated behaviors, including superconductivity and flavor polarization, will be discussed in these twisted multilayer graphene systems, seeking the relationship between broken symmetry states and superconductivity that appeared in these systems.