Activation Energies of the Fractional Quantum Hall Effect in GaAs/AlGaAs Heterostructures

Abstract

Temperature dependence of the diagonal resistivity ρ_xx at the minimum of the 1/3 and 2/3 fractional quantum Hall effect has been measured for GaAs/AlGaAs heterostructures having wide variety of mobility. The results are well expressed by assuming two activated conduction processes. The activation energies in high temperature region do not show a systematic dependence on the magnetic field B but on the μB, where μ is the electron mobility at zero field. The activation energy for the 2/3 effect is about one third of that for the 1/3 effect when scaled by μB. This result shows that there is no electron-hole symmetry in the experimental activation energy.