Abstract
We investigate the resonance conductance of a quantum point contact (QPC), defined in a two-dimensional electron gas of a high-mobility GaAs/AlGaAs heterojunction. The potential profile of the QPC channel can be locally tuned by separately biasing the split gate and a cross gate, electrically isolated on the top of the QPC. The conductance, evolving with the cross-gate voltages exhibits an oscillatory feature superimposed on the quantized plateau in the positive bias voltages and a suppression of the plateau in negative bias voltages. Our investigation suggests that the oscillations on the conductance result from the longitudinal resonance through the channel. The governing parameters of the resonance are the aspect ratio of the channel and the Fermi wavelength of the incident electrons. © 2010 The American Physical Society.