Topological mixed valence model in magic-angle twisted bilayer graphene

We develop a model to describe the mixed valence regime in magic-angle twisted bilayer graphene (MATBG) using the recently developed heavy-fermion framework. By employing the large-N slave-boson approach, we derive the self-consistent mean-field equations and solve them numerically. We find that the SU(8) local flat-band electron symmetry constraint moir\'e system exhibits mixed valence properties that are different from conventional heavy-fermion systems. We find the solutions describing the physics at the filling near the Mott insulator regime in the limit of strong Coulomb interactions between the flat-band fermions. Our model can provide additional insight into the possible microscopic origin of unconventional superconductivity in MATBG.