Persistent currents in mesoscopic rings with a quantum dot

Abstract

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 $\ensuremath{\Phi}$ for different ring length L, temperature T, and broadening of the conduction states $\ensuremath{\delta}.$ For $T=\ensuremath{\delta}=0$ and $L\ensuremath{\gg}\ensuremath{\xi},$ where $\ensuremath{\xi}$ 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 $L/\ensuremath{\xi},$ $\mathrm{Lj}$ is also suppressed when either T or $\ensuremath{\delta}$ increase above a fraction of the level spacing, which depends on $\ensuremath{\Phi}.$