Transport through side-coupled multilevel double quantum dots in the Kondo regime

Abstract

We analyze the transport properties of a double quantum dot device in the\nside-coupled configuration. A small quantum dot (QD), having a single relevant\nelectronic level, is coupled to source and drain electrodes. A larger QD, whose\nmultilevel nature is considered, is tunnel-coupled to the small QD. A Fermi\nliquid analysis shows that the low temperature conductance of the device is\ndetermined by the total electronic occupation of the double QD. When the small\ndot is in the Kondo regime, an even number of electrons in the large dot leads\nto a conductance that reaches the unitary limit, while for an odd number of\nelectrons a two stage Kondo effect is observed and the conductance is strongly\nsuppressed. The Kondo temperature of the second stage Kondo effect is strongly\naffected by the multilevel structure of the large QD. For increasing level\nspacing, a crossover from a large Kondo temperature regime to a small Kondo\ntemperature regime is obtained when the level spacing becomes of the order of\nthe large Kondo temperature.\n