Magnetic Field Symmetry Properties of the Capacitance Tensor of a Two-Dimensional Electron System

Large, almost complete, asymmetry in the capacitance tensor elements is observed under field reversal in a 2D electron system with a multilead measurement configuration. In our high mobility electron gas the saturation field for this asymmetry is typically less than 0.05 T at $T<4$ K. The measured magnetic field symmetries are consistent with a recent theoretical discussion of capacitance by B\"uttiker and are in accordance with the Onsager-Casimir symmetry requirements. In multilead structures capacitance coefficients which are uneven under magnetic field reversal are possible since the Coulomb interaction couples a partial density of states instead of the full equilibrium density of states.