The magnetocapacitance of a two-dimensional electron system (2DES) is investigated experimentally, both under the and away from quantum Hall conditions, at frequencies between 1 kHz and 100 MHz. The nature of the capacitive signal in a bounded 2DES is determined by a resistive cutoff frequency $1/\tau \propto {\sigma }_{\mathrm{xx}}$, the longitudinal magnetoconductivity. A new response mechanism is reported for angular frequencies $\omega >1\mathrm{}/\tau$, which is controlled by the transverse or Hall conductivity ${\sigma }_{\mathrm{xy}}$ and the boundaries of the sample. The mechanism is also found at frequencies far below those of the edge magnetoplasma resonances and away from the quantum Hall regime.

• Received 11 June 1998

DOI:https://doi.org/10.1103/PhysRevLett.81.5398