Fractional quantum Hall effect in a high-mobility GaAs/AlxGa1−xAs multiple quantum well heterostructure

We report the realization of a high mobility [μ≂4.8×105 cm2/(V s)] selectively doped GaAs/AlxGa1−xAs multiple quantum well structure with low density (ns ≂1.7×1011 cm−2 for each of the 85 wells) grown by molecular beam epitaxy. The activation energy for the fractional quantum Hall state at the Landau-level filling factor ν=1/3 is Δ≂2 K, the highest value ever reported for any multiple quantum well structure. Such a structure is nearly ideal for studies of the thermal properties of the two-dimensional electron system in the fractional quantum Hall regime.