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

摘要

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