Different Behaviour of Integral and Fractional Quantum Hall Plateaus in GaAs-AlxGa1−xAs Heterostructures Under Back-Gating and Illumination
We measured the Shubnikov-de Haas resistivity of a 2-dimensional electron-gas (2DEG) in GaAs/A1GaAs heterojunctions and compared measurements in which for the same sample the electron density was increased to the same value either by back-gating or illumination. The electron-impurity interaction is different in these two cases. We observed that the integral and fractional Quantum-Hall (QH) plateaus behave quite differently in these two cases. We conclude that the integral Quantum-Hall Effect (IQHE) becomes stronger for stronger electron-impurity interaction while the fractional Quantum-Hall Effect (FQHE) is destroyed. This is consistent with the idea that the IQHE is due to electron-impurity interaction while the FQHE is based on electron-electron interaction.
KeywordsDilution Refrigerator Electron Density Increase 2Philips Research Laboratory Magnet Laboratory Initial Electron Density
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