Transport in coupled quantum dots:: Kondo effect versus antiferromagnetic correlation

The interplay between the Kondo effect and the interdot magnetic interaction in a coupled-dot system is studied. An exact result for the transport properties at zero temperature is obtained by diagonalizing a cluster, composed by the double dot and its vicinity, which is connected to leads. It is shown that the system goes continuously from the Kondo regime to an antiferromagnetic state as the interdot interaction is increased. The conductance, the charge at the dots, and the spin-spin correlation are obtained as a function of the gate potential.