transition metal kagome compound*

The kagome lattice can host both Dirac electrons and the flat band in the spectrum. With spin-orbit coupling, the flat band will acquire non-trivial topology. On the other hand, when the kinetic energy scale is quenched as with a flat band, the electron interactions could facilitate the formation of correlated phases. Hence, the kagome lattice system has the potential to open a door to study the interplay between topology and electron correlations. In synthesized kagome compounds, additional degrees of freedom such as the orbitals further enrich the physics. To elucidate the nature of the electronic structure, we perform the ab initio density functional theory calculations. We focus on the 3d transition metal kagome compound with topological flat bands, observed experimentally by angle-resolved photoemission spectroscopy. The effective Hamiltonians of these topological flat bands are investigated with the derivations of Wannier states. The implications of topological obstructions and crystalline symmetries are discussed. These localized Wannier functions with intricate spin and orbital texture in the real space reveal their origin from the frustrated kagome structure.