Quantised Hall effect and magnetoresistance through a quantum point contact

Abstract
The four-terminal magnetoresistance and quantised Hall effect through a quantum point contact are investigated in a two-dimensional electron gas (2DEG) based on an n-type (AlGa)As/GaAs single heterostructure. Depending on the choice of current and voltage contacts we measure three different magnetoresistances in a quantising magnetic field. The results agree with a simple model based on conduction via edge states and also with a more conventional analysis based on the properties of a bulk 2DEG.