Control of Aharonov-Bohm oscillations in a AlGaAs/GaAs ring by asymmetric and symmetric gate biasing

The control of the Aharonov-Bohm effect on a AlGaAs/GaAs ring structure is studied by employing two in-plane-gates. By applying a gate voltage to one of the gates, a change of the oscillation pattern due to the additional pot ential induced in one branch of the ring is observed. The change of the osc illation frequency as well as the phase is attributed to the multi-channel transport. In case of a symmetric biasing, where both gates are biased simu ltaneously, a larger voltage is required to change the oscillation pattern than for the case when only one gate is used, This effect is explained by a partial compensation of the phase difference between both branches of the ring. (C) 2001 Elsevier Science B.V. All rights reserved.