Contactless measurements of the internal capacitance of a Corbino ring in the quantum Hall regime

A fully inductive technique has been used to observe the quantum Hall effect without any electrical connection to the two-dimensional electron gas. The ac response of the measuring system is described by a model taking into account the effect of the intrinsic capacitance of the Corbino ring. This internal capacitance is on the order of 100 pF/m for a 1 mm wide sample, a value which is not negligible in the field of ac quantum metrology.