Detection of the oscillation of the Fermi energy of a 2DEG

We have used a quantum antidot (QAD) to detect the oscillation of the Fermi energy in a two-dimensional electron gas (2DEG) as a function of magnetic field. At a magnetic field B-sic = n(s)h(2)/(e(2) pi R(2))(where n(s) is the carrier density and R is the radius of the QAD at the Fermi energy) the Shubnikov-de Haas (SdH) oscillation period becomes greater than the period of the Aharonov-Bohm (AB) oscillations from the QAD. Hence, above this field, the corresponding oscillation of the Fermi energy is superimposed onto the period of the AB oscillations. We have taken measurements of the AB period as a function of magnetic field at a number of different QAD radii. These measurements reveal an average oscillatory period which is consistent with the motion of the Fermi energy through the predicted QAD eigen spectrum.