Equipotential distribution in the quantum Hall effect in GaAs-AlGaAs heterostructures

Abstract
The authors have measured the equipotential distribution in modulation-doped GaAs-AlGaAs heterojunctions while observing the quantum Hall effect (QHE), at T=4.2K and 2.2K. They present equipotential maps at various applied magnetic fields and discuss the changes in the equipotential distribution in quantised Hall plateau regions, where the Fermi level moves between Landau levels and the magnetoresistance, rho xx, approaches zero. The charge and current distributions within the specimens may be inferred from the equipotential patterns. The authors extend the observations of others on the internal impedance of QHE samples to include the case of interior contacts.