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HL: Fachverband Halbleiterphysik
HL 18: Quantum Hall Effect
HL 18.1: Talk
Monday, March 14, 2011, 14:30–14:45, POT 151
Huge Magnetoresistance in a High Mobility Two-Dimensional Electron Gas — •Lina Bockhorn1, Patrick Barthold1, Dieter Schuh2, Werner Wegscheider3, and Rolf J. Haug1 — 1Institut für Festkörperphysik, Leibniz Universität Hannover — 2Institut für Experimentelle und Angewandte Physik, Universität Regensburg — 3ETH Zürich, Switzerland
We study the fractional Quantum-Hall effect in high mobility two-dimensional electron gas (2DEG). Hall geometries are created by photolithography on a GaAs/GaAlAs quantum well containing a 2DEG. The 2DEG have an electron density of ne=3.1*1011cm−2 and a mobility of µe=11.9*106cm2/Vs at a temperature of 1.5 K.
We observe a strong negative magnetoresistance at zero magnetic field. In lowering the electron density the magnetoresistance gets more pronounced and reaches values of more than 300%. We observe that the huge magnetoresistance vanishes for increasing the temperature. An additional density dependent factor is introduced to be able to fit the parabolic magnetoresistance to the electron-electron interaction correction.
A discrepancy between theory and experiment is observed. A possible origin could be that the influence of the density fluctuation for high mobility 2DEG is not correctly described by theory. In our high mobility samples a very small, but finite density variation across the sample induces an additional long range potential, up to now not treated in theory.
arXiv:1012.0168