Interference effects and Fano resonance in transport across a two dot system in the Kondo regime

Transport across a double dot system of a special geometry with two channels accessible for tunneling electrons is theoretically studied in a region of low temperatures corresponding to the Kondo regime, and interference effects are analyzed. The spectral function and the linear conductance are calculated using the Green function formalism based on the equation of motion method. It is shown that interference processes strongly influence the spectral function. Moreover, due to interference effects the conductance, which is close to zero in a low energy region, shows at higher gate voltages a well defined Fano resonance. A development of the Fano peak as the system undergoes a gradual transition from the serial configuration to the geometry with two dots partially connected to both electrodes is demonstrated. The position and intensity of the Fano resonance strongly depend on the inter-dot tunneling rate. The influence of temperature on the resonance is also discussed.