Anomalous Kondo-Switching Effect of a Spin-Flip Quantum Dot Embedded in an Aharonov-Bohm Ring

We theoretically investigate the Kondo effect of a quantum dot embedded in a mesoscopic Aharonov-Bohm (AB) ring in the presence of the spin flip processes by means of the one-impurity Anderson Hamiltonian. Based on the and size of the AB ring an slave-boson mean-field theory, we find that in this system the persistent current (PC) sensitively depends on the parity can be tuned by the spin-flip scattering (R). In the small A Bring, the PC is suppressed due to the enhancing R weakening the Kondo resonance. On the contrary, in the large AB ring,with R increasing, the peak of PC firstly moves up to max-peak and then down. Especially,the PC phase shift of pi appears suddenly with the proper value of R, implying the existence of the anomalous Kondo effect in this system. Thus this system may be a candidate for quantum switch.