Dresden 2003 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 22: Hauptvortrag Hohls

HL 22.1: Hauptvortrag

Dienstag, 25. März 2003, 14:30–15:15, POT/81

Scaling of the Quantum Hall Plateau Transition — •Frank Hohls — Universität Hannover, Institut für Festkörperphysik, Abteilung Nanostrukturen, Appelstr. 2, D-30167 Deutschland

The crossover regions between plateaus of the integer quantum Hall effect (IQHE) can be described in the framework of quantum phase transitions on the basis of a scaling theory. Many experimental and theoretical investigations have been undertaken to prove the validity of this description. One mayor touchstone is the universality of this phenomenon: Theory expects universal scaling exponents independent of any sample properties. I will discuss experiments illuminating different aspects of the plateau transition: Temperature and frequency dependent measurements of the conductivity in the variable range hopping regime allow to determine the localization length and the critical exponent of this quantum phase transition [1,2]. High frequency measurements at the transition, realized on various samples and in different setups, can be combined to demonstrate the universal nature of this phenomenon and allow to determine the dynamical exponent [3]. The effect of finite temperature is further examined by investigations of conductance fluctuations at the plateau transition for mesoscopic samples [4]. In their entirety all these experiments affirm the picture of a universal scaling of the IQHE plateau transition.

[1] F. Hohls, U. Zeitler, and R. J. Haug, PRL 86, 5124 (2001)

[2] F. Hohls, U. Zeitler, and R. J. Haug, PRL 88, 036802 (2002)

[3] F. Hohls et. al., PRL 89, 276801 (2002)

[4] F. Hohls, U. Zeitler, and R. J. Haug, PRB 66, 073304 (2002)