Conductance oscillations in a deformable quantum ring

Low temperature magnetoconductance oscillation measurements are reported for a deformable quantum ring. The quantum ring is formed from a two-dimensional electron gas in a GaAs/Al0.3Ga0.7As heterostructure via electrostatic gates: outside gates define the outer perimeter with two quantum point contacts and a separately contacted center gate forms a central hole with adjustable size. Three lithography layers, aligned to 50 nm precision, were required to achieve independent contact to the center gate. Series of magneto-oscillation power spectra for increasing size of the central hole show two sets of peaks: one at essentially constant magnetic frequency corresponding to the area enclosed by the outer circumference as for edge-state interference and one which shifts to lower frequency corresponding to the area of the electron ring. Copyright (C) 1996 Elsevier Science Ltd