Speaker: Allan MacDonald (University of Texas at Austin)
Title: Known Knowns and Known Unknowns in MATBG
Abstract: At a magic angle (MA) near 1 degree, the moiré superlattice bands of twisted bilayer graphene (TBG) become extremely flat converting gated graphene sheets from benign Fermi liquids to interesting strongly correlated electron systems. I will discuss progress in understanding the electronic properties of MATBG, concluding that q=0 broken spin/valley flavor symmetries are common in insulating and metallic states, and that (the strongest) superconductivity emerges from electron-pairing in a ferromagnetic parent state. I will also highlight some important theoretical blind spots including the pairing mechanism, which is of course often a challenge in superconductors, but also some important details of the underlying electronic structure at fractional filling factors.