Effect of δ barrier on persistent current in a quantum ring with multiple arms

Abstract

A new model of quantum ring with multiple arms containing δ barrier is proposed in this paper. The results imply that the persistent current shows behavior of nonperiodic oscillation with the size of the semiconductor ring increasing when the total magnetic flux is zero. The lower arm obtains minimal average persistent current because it contains the δ barrier. The persistent current generates periodic oscillation when the AB magnetic flux strengthens. It is related to not only the electrodes’ magnetic moment direction but also the tunneling electrons’ spin orientation. Furthermore, when the two magnetic moments are parallel, the Rashba spin-orbit interaction has the effect of changing the persistent current’s phase and phase difference. However, when the magnetic moments in the two electrodes are antiparallel, the Rashba spin-orbit interaction affects the amplitude of the persistent current. Our results also indicate that the difference of the persistent current in each arm is retated to the arm length and the magnetic flux’s distribution. The persistent currents which the two kind of wave functions correspond to are separated under definite conditions.