High frequency conductivity in the quantum Hall effect

We present high frequency measurements of the diagonal conductivity sigma_xx of a two dimensional electron system in the integer quantum Hall regime. The width of the sigma_xx peaks between QHE minima is analyzed within the framework of scaling theory using both temperature T=100-700 mK and frequency f <= 6 GHz in a two parameter scaling ansatz. For the plateau transition width we find scaling behaviour for both its temperature dependence as well as its frequency dependence. However, the corresp...