Composite Hofstadter bands with Dirac fermion spectrum of fractional quantum Hall states

The fractional quantum Hall effect (FQHE) is studied in the semiclassical limit in the framework of the Hofstadter model with a short-range interaction between fermions. In the mean-field approximation, the repulsion between fermions leads to a periodic potential. Numerical calculations show that in the case of the periodic potential with a period that is a multiple on 1 of the magnetic cell (is filling of a separated band) composite Hofstadter bands (HBs) are formed. The composite HBs are split into 1 subbands, which are separated by the Dirac points. The Chern number of -full filled composite HBs is equal to the Chern number C_ of the corresponding HB. The Chern number, equal to C_, corresponds to -filling of -composite HB. Thus, FQHE is realized by fractional filling of composite HBs.