Conductance Fluctuations on the Quantum Hall Plateaus in GaAs/AlGaAs
The gauge invariance arguments of Laughlin imply perfect quantization of the quantum Hall plateaus /1/ and Hall voltage measurements using digital time-averaging, null detection techniques at fixed values of the magnetic field have shown that the Hall plateaus are flat to ∼ 0.01 parts in 106 (i.e. 0.01 ppm) /2/ even though the current path within the sample switches continuously with the magnetic field over the field range defined by the plateau region /3/. Although the Hall steps are flat at the lowest temperatures, ρxy can deviate from h/ve2 by up to several ppm, following the relation ∆ρxy = ρxy(T) − ρxy (0) ∼ sρxx min with s a sample dependent parameter of order 1 /2/. This high degree of quantization has possibly set new resistance standards while motivating considerable theoretical work on the role of disorder in high field 2D transport.
KeywordsQuantum Hall Effect Defense Advance Research Project Agency Conductance Fluctuation Hall Plateau Quantum Hall Regime
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