MAGNETOCAPACITANCE AND THE EDGE STATE OF A 2-DIMENSIONAL ELECTRON-SYSTEM IN THE QUANTUM HALL REGIME

The magnetic field dependence of the capacitance of a GaAs/AlGaAs heterostructure through a two-dimensional electron system (2DES) is measured in the quantum Hall regime. The capacitance minima at the Hall plateaus are determined not by the 2DES area under the gate but by the edge length of the 2DES, which cannot be explained by an existing interpretation of the magnetocapacitance, where the capacitance is directly related to the 2DES density of states. We suggest an alternative model: the bottom values are essentially determined by the edge current carrying area. The widths of the current channels are estimated and compared with recent theoretical and experimental estimates.