Heavy-Fermion Phase Diagram in Magic-Angle Twisted Trilayer Graphene.

The interplay between localized magnetic moments and itinerant electrons gives rise to exotic quantum states in condensed matter systems. Here, we demonstrate an electrically tunable heavy fermion phase diagram in magic-angle twisted trilayer graphene, achieved by controlling the Kondo hybridization between localized flat-band electrons and itinerant Dirac electrons via a displacement field. Our results reveal a continuous quantum phase transition from an antiferromagnetic semimetal to a paramagnetic heavy fermion metal. At the quantum critical point, we observe effective mass divergence and Fermi surface reconstruction. This highly tunable platform offers unprecedented control over heavy fermion physics, establishing moiré heterostructures as a versatile arena for exploring correlated quantum phases-including potential unconventional superconductivity-in the two-dimensional limit.