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 theslave-boson mean-field theory,we find that in this system the persistent current(PC)sensitively depends on the parityand size of the AB ring and can be tuned by the spin-flip scattering(R).In the small AB ring,the PC is suppresseddue to the enhancing R weakening the Kondo resonance.On the contrary,in the large AB ring,with R increasing,thepeak of PC firstly moves up to max-peak and then down.Especially,the PC phase shift of π appears suddenly withthe proper value of R,implying the existence of the anomalous Kondo effect in this system.Thus this system may be acandidate for quantum switch.