Competition between crystal and fractional quantum Hall liquid in the presence of LL mixing

In low-density hole-type GaAs quantum wells, an insulating phase is observed for ν < 1/3 and also between ν = 1/3 and ν = 2/5. In a fixed phase diffusion Monte Carlo calculation, we find re-entrant phase transitions for a range of LL mixing, where the system goes, with increasing magnetic field, from 2/5 FQHE liquid → crystal → 1/3 FQHE liquid → crystal. Our results are in excellent agreement with experiments. It is predicted that for yet higher LL mixing, the crystal phase altogether suppresses the 1/3 and 2/5 FQHE. We also consider the filling factors ν = 1/5 and ν = 2/9 and predict that with increasing LL mixing a transition occurs into a crystal of composite fermions carrying two vortices.