Fractional Quantum Hall Effect and Wigner Crystal of Two-Flux Composite   Fermions
  In two-dimensional electron systems confined to GaAs quantum wells, as a function of either tilting the sample in magnetic field or increasing density, we observe multiple transitions of the fractional quantum Hall states (FQHSs) near filling factors $\nu=3/4$ and 5/4. The data reveal that these are spin-polarization transitions of interacting two-flux composite Fermions, which form their own FQHSs at these fillings. The fact that the reentrant integer quantum Hall effect near $\nu=4/5$ always develops following the transition to full spin polarization of the $\nu=4/5$ FQHS strongly links the reentrant phase to a pinned \emph{ferromagnetic} Wigner crystal of two-flux composite Fermions. 
Yang Liu, D. Kamburov, S. Hasdemir, M. Shayegan, L.N. Pfeifer, K.W.   West, and K.W. Baldwin
cond-mat.mes-hall cond-mat.str-el