Persistent currents in mesoscopic rings with a quantum dot

Using the Anderson model in the Kondo regime, we calculate the persistent current j in a ring with an embedded quantum dot (QD) as a function of the Aharonov-Bohm flux Phi for different ring length L, temperature T, and broadening of the conduction states delta. For T=delta=0 and L>>xi, where xi is the Kondo screening length, Lj tends to the value for a noninteracting ideal ring, while it is suppressed for a side-coupled QD. For any L/xi, Lj is also suppressed when either T or delta increase above a fraction of the level spacing, which depends on Phi.