Incompressible, metallic and insulating states of two-dimensional systems: Recent experiments

This paper provides a brief summary of some recent experimental results regarding the states of two-dimensional electron systems at high magnetic fields. The states include the incompressible, quantum Hall liquid at integer and fractional Landau-level fillings, the metallic-like state of the flux-particle composite Fermions at half-filling and the insulating phase at low fillings. Some unifying features of these states and their interrelation are also discussed.