Edge States in the Fractional Quantum Hall Effect Regime Investigated by Magnetocapacitance

The magnetocapacitance between a two-dimensional electron system (2DES) and the gate electrode on it has been measured in the fractional quantum Hall effect regime. By measuring the edge-length dependence of the magnetocapacitance, we show that the conducting region (the edge state) is formed along the sample boundary. The width of edge state (Wₑ) and the bulk conductivity of the 2DES are estimated from the frequency dependence of the magnetocapacitance. The estimated Wₑ is much wider than that expected from the one-electron approximation picture in the integer quantum Hall regime.