Measurements of the compressibility of the composite fermion metallic state in a 2D electron system

It is well-established that the electron–electron interaction strongly affects the compressibility of a two-dimensional electron system at zero magnetic field and even leads to the negative sign of the compressibility. Surprisingly, we find that its contribution is almost identical for the metallic states of electrons at zero magnetic field and of composite fermions at Landau level filling View the MathML source.