Realization of Kagome Kondo lattice

The Kondo lattice, describing a grid of the local magnetic moments coupling to itinerant electrons, is a fertile ground of strongly correlated states in condensed matter physics. While the Kagome lattice has long been predicted to host Kondo physics with exotic magnetism and nontrivial topology, no experimental realization has been achieved to the best of our knowledge. Here, we report the discovery of CsCr₆Sb₆, a van der Waals-like Kagome Kondo lattice featuring extremely flat, isolated bands at the Fermi level that composed entirely of Cr-3d electrons. We observe heavy fermions with the effective mass over 100 times greater than those of its vanadium counterpart. We also observe Kondo insulating behavior in an ultra-low carrier density of 10¹⁹cm^-3 and dimensionality-induced Kondo breakdown. Counterintuitively, mechanical exfoliation of the frustrated bulk reveals hidden A-type antiferromagnetism with even-odd layer-dependent anomalous Hall effect. The realization of Kondo physics in Kagome lattice opens avenues for exploring diverse quantum criticalities in a strongly-correlated frustrated system.