High frequency conductivity in the quantum hall regime.
We have measured the complex conductivity sigma(xx) of a two-dimensional electron system in the quantum Hall regime up to frequencies of 6 GHz at electron temperatures below 100 mK. Using both its imaginary and real part we show that sigma(xx) can be scaled to a single function for different frequencies and several transitions between plateaus in the quantum Hall effect. Additionally, the conductivity in the variable-range hopping regime is used for a direct evaluation of the localization length xi. Even for large filling factor distances deltanu from the critical point we find xi approximately equals deltanu(-gamma) with a scaling exponent gamma = 2.3.
Hohls
F
F
Institut für Festkörperphysik, Universität Hannover, Applestrasse 2, 30167 Hannover, Germany. hohls@nano.uni-hannover.de
Zeitler
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Haug
R J
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