The stacking of two similar lattices produces a moiré pattern which is a large spatial period superlattice. Experimentally, a large class of 2D moiré materials can be created using this method, which has attracted extensive interests recently. A paradigm is the twisted bilayer graphene (TBG), which generates topological flat bands of electrons at the so-called magic angle (1.1 degrees), and exhibits superconductivity and correlated insulator phases. I will talk about the systematic theory of TBG with Coulomb interactions, which has an approximate U(4) symmetry and interacting Chern insulator ground states at integer fillings. I will further present alternative setups of moiré graphene hosting magic flat bands in effective kagome and honeycomb moiré lattices, particularly twisted Kekulé graphene. These systems provide promising new platforms for studying novel strongly correlated phases of matter.

Bio: Dr. Lian Biao is an assistant professor at the Department of Physics, Princeton University. He received his B.Sc. from the Department of Physics, Tsinghua University in 2012, and completed his Ph.D. study from Stanford University in 2017. He then worked as a postdoctoral fellow in Princeton Center for Theoretical Science from 2017 to 2020. His research interests are theoretical condensed matter physics and nonequilibrium many-body quantum systems. He received awards including Sloan Research Fellowship (2021) and NSF early career award (2022).