The Influence of Contacts on the Quantized Hall Effect
The influence of electrical contacts on the magnetotransport in the quantized Hall regime is measured on various geometries in GaAs - A1xGa1−xAs heterostructures. The observed effects are interpreted in terms of a local resistivity tensor without taking into account the possible existence of macroscopic quantum states or localization. In special geometries with large contacts we measure, and explain, a two-terminal resistance that is smaller than the Hall resistivity. Furthermore the effects of large Hall contacts in a normal Hall bar geometry are calculated and we show why the measured Hall resistance can be smaller than the true Hall resistance, with their difference proportional to the magnetoresistance, leading to a dip at the strong-field side of Hall plateaus. This extends our interpretation in terms of a (inhomogeneous) local resistivity tensor to real samples with metal contacts.
KeywordsCage GaAs Harman
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