Coulomb oscillations of the Fano-Kondo effect and zero bias anomalies in the double dot meso-transistor

TL;DR

This paper theoretically studies the transport properties of a double quantum dot system, revealing how Coulomb oscillations, Fano interference, and Kondo effects interplay, leading to controllable conductance features and zero bias anomalies.

Contribution

It introduces a detailed theoretical analysis of Fano-Kondo effects in double quantum dots, including the impact of interference and Coulomb blockade on conductance and zero bias anomalies.

Findings

Coulomb oscillations exhibit Fano profiles controlled by temperature and gate potential.

Zero bias conductance anomalies can be enhanced or suppressed, showing Fano zero effects.

Scaling properties of conductance are analyzed using advanced theoretical models.

Abstract

We investigate theoretically the transport properties of the side-coupled double quantum dots in connection with the experimental study of Sasaki {\it et al.} Phys.Rev.Lett.{\bf 103}, 266806 (2009). The novelty of the set-up consists in connecting the Kondo dot directly to the leads, while the side dot provides an interference path which affects the Kondo correlations. We analyze the oscillations of the source-drain current due to the periodical Coulomb blockade of the many-level side-dot at the variation of the gate potential applied on it. The Fano profile of these oscillations may be controlled by the temperature, gate potential and interdot coupling. The non-equilibrium conductance of the double dot system exhibits zero bias anomaly which, besides the usual enhancement, may show also a suppression (a dip-like aspect) which occurs around the Fano {\it zero}. In the same region, the weak temperature dependence of the conductance indicates the suppression of the Kondo effect. Scaling properties of the non-equilibrium conductance in the Fano-Kondo regime are discussed. Since the SIAM Kondo temperature is no longer the proper scaling parameter, we look for an alternative specific to the double-dot. The extended Anderson model, Keldysh formalism and equation of motion technique are used.