Topological flat bands in a kagomé lattice multiorbital system

Abstract

Flat bands and dispersive Dirac bands are known to coexist in the electronic bands in a twodimensional kagomé lattice. With the relativistic spin-orbit coupling, such systems often exhibit nontrivial band topology, allowing gapless edge modes between flat bands and dispersive bands or at the Dirac band crossing. Here, we theoretically demonstrate that a multiorbital system on a kagomé lattice is a versatile platform to explore the interplay between interaction and nontrivial band topology. When a flat band is 1/3 filled, non-local repulsive interactions further induce a fractional quantum Hall state. We also discuss the possible realization of our findings in real kagomé materials.