Self-consistent analysis of a quantum capacitor

We analyze the behavior of the magnetocapacitance for a three-probe capacit or. The self-consistent evaluation of the internal potential is found to pl ay a large role in determining quantitative values of the capacitance. For capacitor plates of mesoscopic size, this potential reduces the charge accu mulation by more than an order of magnitude compared to that obtained with noninteracting models. However, the qualitative behavior of the magnetocapa citance is not substantially altered by the self-consistency. A simple but physically motivated model gives an analytical formula which compares well with the numerical data. [S0163-1829(98)05347-8].