Spin-orbit coupling effect on persistent currents in a one-dimensional quantum ring with an Anderson impurity

Based on the finite U slave boson method, we have investigated the effect of Rashba spin-orbit (SO) coupling on the persistent charge and spin currents in a one-dimensional quantum ring with a magnetic impurity. We have used a tight-binding model in the momentum space for electrons in the ring and the Anderson impurity model for the magnetic impurity. It is shown that the Kondo effect will decrease the magnitude and change the curve shape of the persistent charge and spin currents significantly in this side-coupled Anderson impurity case. In the presence of SO coupling, the persistent currents change drastically and show oscillations with the strength of SO coupling alpha(R). The direction of the persistent current can be reversed by tuning alpha(R). For the system with an odd number of electrons, there are abrupt jumps of the persistent currents at the position of level crossing. It is also found that a persistent spin current circulating the ring can exist even without the charge current in this system.