Nonlinearity of acoustic effects and high-frequency electrical conductivity in GaAs/AlGaAs heterostructures under conditions of the integer quantum Hall effect

Abstract

The absorption coefficient for surface acoustic wave Γ and variation in the wave velocity ∆V /V were measured in GaAs/AlGaAs heterostructures; the above quantities are related to interaction of the wave with two-dimensional electron gas and depend nonlinearly on the power of the wave. Measurements were performed under conditions of the integer quantum Hall effect (IQHE), in which case the two-dimensional electron gas was localized in a random fluctuation potential of impurities. The dependences of the components σ1(E) and σ2(E) of high-frequency conductivity σ = σ1 − iσ2 on the electric field of the surface wave were determined. In the range of the conductivity obeying the Arrhenius law (σ1 ≫ σ2), the results obtained are interpreted in terms of the Shklovskii theory of nonlinear percolation-based conductivity, which makes it possible to estimate the magnitude of the fluctuation potential of impurities. The dependences σ1(E) and σ2(E) in the range of highfrequency hopping electrical conductivity, in which case (σ1 ≪ σ2) and the theory of nonlinearities has not been yet developed, are reported.