ELECTROSTATIC AHARONOV-BOHM CONDUCTANCE OSCILLATIONS IN A MESOSCOPIC RING - EFFECTS OF POTENTIAL DISCONTINUITIES

Quantum oscillations in a mesoscopic ring with two leads are studied w here a magnetic flux and an electrostatic potential are applied simult aneously. Ballistic transport is investigated where electrons pass thr ough the entire system without being scattered except at the junction of the ring and the lead. The effects of magnetic flux threading the r ing can be considered as a phase shift in an Aharonov-Bohm (AB) sense. In the electrostatic AB effects, the effects of electrostatic potenti al applied to either of the two electron paths has so far been conside red in terms of the electrostatic phase shift (model A), In a mesoscop ic system (or in a rigorous theoretical treatment), we must consider t he additional effects of scattering due to potential discontinuities a t the edges of the electrode to which the electrostatic potential is a pplied (model B). In this paper, models A and B are considered on an e qual footing. By comparing these two cases, we find that the conventio nal treatment of AB effects is possible at low electrostatic potential in a mesoscopic system. In model B, where the scattering effects at t he gate edges are considered, the amplitudes of the quantum oscillatio n slowly decay as a function of increasing electrostatic potential. At higher electrostatic potential, we predict that conductance oscillati ons exhibit strong resonance structures at the maximum plateau regions . The relation between the transmission probability and electron energ y is also calculated for fixed theta and phi, and discussed.