Topological phase transitions and topological flat bands on the ruby lattice

Abstract

We investigate the topological properties of a tight-binding model on the two-dimensional ruby lattice in the presence of staggered fluxes. The variation of the nearest- and next-nearest-neighbor hopping parameters yields tunable Chern-number bands, which may host quantum anomalous Hall insulators at different filling fractions. Interestingly, we obtain topological nontrivial bands with high Chern number C = −4. We show that topological phase transitions among different gapped phases are accompanied with the gap closing and reopening processes. Furthermore, we find topological flat bands with Chern number C=+1, which could be a platform for realizing a fractional quantum Hall effect.