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

AbstractThe 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 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 , the results obtained are interpreted in terms of the Shklovski $$\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{l}$$ 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 high-frequency hopping electrical conductivity, in which case and the theory of nonlinearities has not been yet developed, are reported.