Kagome Hubbard model away from the strong coupling limit: Flat band localization and non Fermi liquid signatures

Taking cue from the recent experimental realization of metallic phases in Kagome materials we report the low temperature signatures and thermal scales of Kagome metals and insulators, determined in the framework of the Kagome Hubbard model, using a non perturbative numerical approach. In contrast to the existing consensus we establish a flat band localized insulator in the weak coupling regime which crosses over to a non Fermi liquid (NFL) metal at intermediate coupling, followed by a first order metal-Mott insulator transition in the strong coupling regime. We provide the first accurate estimates of the thermal scales of this model and analyze the NFL phases in terms of resilient quasiparticles and short range magnetic correlations. With our unprecedented access to the low temperature phases and sufficiently large system sizes, we provide the essential benchmarks for the prospective experiments on the Kagome metal and insulators in terms of their thermodynamic, spectroscopic and transport signatures.