Metallic quantum criticality enabled by flat bands in a kagome lattice

Strange metals arise in a variety of platforms for strongly correlated electrons, ranging from the cuprates, heavy fermions to flat band systems. Motivated by recent experiments in kagome metals, we study a Hubbard model on a kagome lattice whose noninteracting limit contains flat bands. A Kondo lattice description is constructed, in which the degrees of freedom are exponentially localized molecular orbitals. We identify an orbital-selective Mott transition through an extended dynamical mean field theory of the effective model. The transition describes a quantum critical point at which quasiparticles are expected to be lost and strange metallicity emerges. Our theoretical work opens up a new route for realizing beyond-Landau quantum criticality and emergent quantum phases that it nucleates.
30 pages, 8 figures