Double quantum dots: Kondo resonance induced by an interdot interaction

We report on an investigation of the Kondo effect induced by an interdot off-site interaction in a double-quantum-dot system. In the limit of zero interdot tunnel coupling (t(C)=0), we discuss a cotunneling process involving the exchange of electron positions between the two quantum dots. At low temperatures this process induces a Kondo resonance with a peculiar characteristic: the Kondo resonance of one dot is pinned at the chemical potential of the lead that is attached to the other dot. When coupling t(C)not equal0, cotunneling processes involving molecular states which span the two dots induce several Kondo resonances in each dot. Then the conductance of the double-dot device shows sharp features including multiple peaks and abrupt drops having typical Kondo character. We discuss the physical origin of these features.