Melting curves and other phase transitions in a two dimensional electron assembly in a transverse magnetic field as a function of the Landau level filling factor

Besides Laughlin/composite Fermion liquid, and Wigner solid, there have been proposals for Hall crystals and condensed phases of skyrmions for inclusion in the QHE systems phase diagram. Some results on Hall crystals are reported, which suggest that at \nu =1/3 such crystals can be the ground state of the 2DEG in a magnetic field. At \nu=1 and 2, Chen et al. experimentally established that the Wigner solid is the ground state. An explanation is also given here for the coexistence in their experiments of an integral QHE plateau and the presence of the Wigner crystal phase near \nu=1. Further, Mandal et al. showed that at \nu =1/7, and most probably at \nu =1/9, an incompressible liquid state should be the ground state. Thus, at least three non-entrant solid phases appear to exist: 0 < nu \leq 1/9, 1/9 < nu \leq 1/7 and,less certainly, 1/7 < \nu \leq 1/5. In addition, points of solid nature are present at \nu =1 and 2 (Wigner solid) and possibly at \nu =1/3 (Hall crystal).