Gate-tunable heavy fermions in a moir\'e Kondo lattice

The Kondo lattice, describing a matrix of local magnetic moments coupled via spin-exchange interactions to itinerant conduction electrons, is a prototype of strongly correlated quantum matter. Traditionally, Kondo lattices are realized in intermetallic compounds containing lanthanide or actinide. The complex electronic structure and limited tunability of both the electron density and exchange interactions in these bulk materials pose significant challenges to study Kondo lattice physics. Here, we report the realization of a synthetic Kondo lattice in AB-stacked MoTe2/WSe2 moir\'e bilayers, where the MoTe2 layer is tuned to a Mott insulating state, supporting a triangular moir\'e 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. We also observe destruction of the heavy fermions by an external magnetic field with an abrupt decrease of the Fermi surface size and quasiparticle mass. We further demonstrate widely and continuously gate-tunable Kondo temperatures through either the itinerant carrier density or Kondo interaction. Our study opens the possibility of in-situ access to the rich phase diagram of the Kondo lattice with exotic quantum criticalities in a single device based on semiconductor moir\'e materials