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 $ΔV/V$ 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 $σ_1(E)$ and $σ_2(E)$ of high-frequency conductivity $σ=σ_1 - iσ_2$ on the electric field of the surface wave were determined. In the range of the conductivity obeying the Arrhenius law ($σ_1 \gg σ_2$), 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 $σ_1(E)$ and $σ_2(E)$ in the range of high-frequency hopping electrical conductivity, in which case ($σ_1 \ll σ_2$) and the theory of nonlinearities has not been yet developed, are reported.