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 $T=\delta =0\mathrm{}$ and $L\gg \xi ,$ where $\xi$ is the Kondo screening length, $\mathrm{Lj}$ tends to the value for a noninteracting ideal ring, while it is suppressed for a side-coupled QD. For any $L/\xi ,$ $\mathrm{Lj}$ is also suppressed when either T or $\delta$ increase above a fraction of the level spacing, which depends on $\Phi .$