The influence of quantum fluctuations on quantum hall phases at large

We have explored the behavior of a two-dimensional hole system in the regime of very low densities and hence large r_s. The electronic phases at the largest magnetic fields have surprising behavior. We found that with decreasing density the reentrant insulating phase weakens until it completely disappears. We also found that at the collapse of the reentrant insulator the nearby fractional quantum Hall liquid is unexpectedly suppressed. Both of these properties can be understood as stemming from quantum fluctuations of the insulating electronic solid.