Temperature Dependence of Transport Coefficients of 2D Electron Systems at Very Small Filling Factors

Abstract

The temperature dependence of the transport coefficients was measured in three GaAs/AlGaAs heterostructures of different quality at small Landau level filling factors υ. The highest quality specimen, as determined by the existence of strong fractional quantum Hall features, exhibits activated conduction as the filling factor approaches υ=0. These characteristics are discussed in terms of magnetic freeze-out and Wigner solid formation.