Investigation of incompressible region by magnetocapacitance measurement in quantum Hall plateaux

We have measured the capacitance between adjacent edge channels (CM) in the GaAs/AlGaAs two-dimensional electron gas in the quantum Hall plateau to investigate the structure of edge channels. The value of CM is mainly determined by the ratio of edge channel width (compressible region) to the separation between them (incompressible region) and the length of the edge channels. However, the energy relaxation between the edge channels reduces the effective length of the adjacent edge channels. Only at ν=3 quantum Hall plateau, it is able to measure CM to investigate the width of incompressible region, since the energy relaxation between the ν=2 and 3 channel is small enough.