Hamburg 2001 – scientific programme
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HL: Halbleiterphysik
HL 15: Quanten-Hall-Effekt
HL 15.5: Talk
Tuesday, March 27, 2001, 11:30–11:45, S16
On the break-down of scaling of the quantum Hall effect in the presence of in-homogeneities — •Josef Oswald — Institute of Physics, University of Leoben, Franz Josef Str. 18, A-8700 Leoben, Austria (e-mail: oswald@unileoben.ac.at)
The temperature dependent scaling of the quantum Hall plateau transitions is the most important basis for comparing experiment and theory. In this context an observation of a Tκ - scaling is considered as an evidence for a quantum phase transition (QPT) at zero temperature. Although the Tκ scaling has been successfully verified by many experiments, there are also quite a number of experiments where a linear scaling function (α + β· T) with a low temperature saturation is found. A major problem in comparing theory and experiment is that none of the theories so far provides results on the basis of Rxx and Rxy for realistic sample structures. Recently we developed a network model for 2D magnetotransport, which makes it possible to study in which way theoretical predictions on a microscopic level map out in Rxx and Rxy of a macroscopic sample. We demonstrate that a Tκ scaling function, which is introduced on the microscopic level of our transport model, can appear as a linear scaling function for Rxx with a significant low temperature saturation if there is a certain amount of macroscopic in-homogeneity in the carrier distribution.