ELECTRON-TRANSPORT IN A NONUNIFORM MAGNETIC-FIELD

We have used MBE regrowth technology to produce a non-planar 2DEG at a GaAs/AlGaAs heterojunction grown over an etched facet. By applying a uniform magnetic field to this structure we obtain a spatially varying field component normal to the 2DEG. When the magnetic field is applied in the plane of the substrate, the resistance measured from one side of the facet to the other is found to be quantized at approximately the quantum Hall plateaux. Rotating the plane of the sample with respect to the magnetic field allows us to investigate edge state propagation and reflection in the different regions of the sample. By making the appropriate four-terminal resistance measurement we can directly determine the filling factor on the facet. In particular we study the novel situation where the transverse field component changes sign on the facet and the cyclotron orbits rotate in the opposite sense to those on the planar region.