Gate-tunable heavy fermions in a moiré Kondo lattice

Moiré materials provide a highly tunable platform for exploring strongly correlated electron phenomena and topological physics. A Mott insulator with local magnetic moments has been realized in semiconductor moiré materials at half-filling of the moiré band. In this talk, I will describe the realization of a synthetic Kondo lattice in MoTe₂/WSe₂ moiré bilayers, where the MoTe₂ layer is tuned to a Mott insulating state, supporting a triangular moiré lattice of local moments and the WSe₂ layer is doped with itinerant conduction carriers. We observe heavy fermions with a large Fermi surface below the Kondo temperature and the destruction of the heavy fermions by an external magnetic field with an abrupt decrease of the Fermi surface size and quasiparticle mass. We also observe a Chern state at the boundary between the light and heavy fermions. Finally, I will demonstrate the emergence of ferromagnetism from a density-tuned Kondo destruction at zero magnetic field.