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))(w here 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 th e QAD. Hence, above this field, the corresponding oscillation of the F ermi energy is superimposed onto the period of the AB oscillations. We have taken measurements of the AB period as a function of magnetic fi eld at a number of different QAD radii. These measurements reveal an a verage oscillatory period which is consistent with the motion of the F ermi energy through the predicted QAD eigen spectrum.