Comparison between the compressibilities of the zero field and composite-fermion metallic states of the two-dimensional electron system - art. no. 121301

We have studied the capacitance between a two-dimensional electron system a nd a gate of field-effect transistors, produced from three different wafers with a single remotely doped GaAs/AlxGa1-xAs heterojunction. In the vicini ty of the Landau-level filling factor v = 1/2, the increment of the capacit ance relative to its zero-magnetic-held value, deltaC(1/2), was found to be insensitive to the carrier density, and close to the value as if the parti cles are noninteracting. This observation implies that electron-electron in teraction affects the compressibility of the zero-field and composite-fermi on metallic states in a very similar manner.