Conductance Through Two Quantum Dots in a Ring: Magnetic Flux Dependence

The conductance of a double-dot system in a ring threaded by a magnetic flux is studied. The ring is connected to two leads in such a way that each dot is embedded in one arm of the structure. The currents going through each arm of the ring are determined by the Aharonov-Bohm effect and the dot charging effects. The conductance for different values of the magnetic flux is obtained as a function of the gate potentials applied to the dots, for two situations: when the dot level energies are equal, ∆E = 0, and when they are different but with ∆E smaller than the Coulomb interaction U . The conductance shows quite distinct behavior according to having a finite or zero magnetic flux threading the ring. The system presents S = 1/2 and S = 1 Kondo phenomena for no magnetic flux and is in the S = 1/2 Kondo regime in the case of half a quantum of magnetic flux.