METALLIC PHASE OF THE QUANTUM HALL SYSTEM AT EVEN-DENOMINATOR FILLING FRACTIONS

We propose an explanation for the resistivity anomalies exhibited by the two-dimensional spin-polarized electron gas at nu = 1/2 and related even-denominator filling fractions. Landau-Ginzburg theory we argue that the inhomogeneity in the electron density, caused by the impurity potential, induces a spatially random distribution of statistical flux, and that electron localization can be suppressed by this random flux. As a result, a metallic phase appears in the phase diagram of the Hall system near nu = 1/2, leading to a temperature-independent resitivity minimum.