Metallic quantum criticality enabled by flat bands in kagome metals

Systems with topological flat bands provide a rich platform for realizing correlation driven novel quantum phases and excitations. They also facilitate fascinating interplay between electronic topology and strong correlations. We investigate flat bands in strongly correlated d-electron-based metallic systems on lattices that realize destructive kinematic interference [1, 2]. We show that the active-band subspace of the metal can be described by an effective Anderson lattice model. Due to the vastly dissimilar bandwidth between the flat and dispersive bands, orbital-selective Mott correlations develop over a broad range of parameters, driving a quantum phase transition between two strongly correlated metallic states with Fermi surfaces of dissimilar sizes. Non-Fermi liquid behaviors emerge in the associated quantum critical regime. We conclude with a discussion on the relevance of our work to the recently observed strong correlation phenomena and signatures of quantum criticality in the kagome compound CsCr3Sb5 [3].

[1] L. Chen et al., arXiv:2212.08017; H. Hu et al., Sci. Adv. 9, eadg0028 (2023).

[2] L. Chen et al., arXiv:2307.09431

[3] Y. Liu et al., arXiv:2309.13514