Fractional Quantum Hall Effect of Hard-Core Bosons in Topological Flat   Bands
  Recent proposals of topological flat band (TFB) models have provided a new route to realize the fractional quantum Hall effect (FQHE) without Landau levels. We study hard-core bosons with short-range interactions in two representative TFB models, one of which is the well known Haldane model (but with different parameters). We demonstrate that FQHE states emerge with signatures of even number of quasi-degenerate ground states on a torus and a robust spectrum gap separating these states from higher energy spectrum. We also establish quantum phase diagrams for the filling factor 1/2 and illustrate quantum phase transitions to other competing symmetry-breaking phases. 
Yi-Fei Wang, Zheng-Cheng Gu, Chang-De Gong, and D. N. Sheng
cond-mat.str-el cond-mat.mes-hall cond-mat.quant-gas quant-ph