Topological flatbands in kagome lattice CaCu5: A first-principles study

Topological flatband materials have garnered significant attention due to their strongly correlated electronic states. Here, we propose the typical flatband and topological features in the classical copper-based kagome lattice CaCu5. Our work confirms the stability of the CaCu5 system. Notably, we identify flatbands in the band structure of the CaCu5 system, accompanied by a typical quadratic band with line touching, and the flatness of flatbands is broken when spin–orbit coupling is introduced. Furthermore, parity and symmetry eigenvalue calculations of the wavefunctions reveal the nontrivial topological properties of the system. Our results suggest that the CaCu5 system, with its topological flatbands, serves as an ideal platform for studying strong correlation effects and novel physical phenomena.