The persistent currents in a triple-arm AB ring with an impurity

Based on quantum waveguide theory, the transmission coefficient and the persistent currents in a multi-arm AB ring with an impurity are investigated theoretically. The numerical results examine the dependence of the persistent currents on the size of the ring and the magnetic flux. Moreover the Fano resonance can be shown by adjusting the systematic parameters. The studies further show that the difference of the persistent currents in the considered system with broken time-reversal symmetry is not only caused by the magnetic flux but also by the different states of electrons in each arm.