Impact of capacitance and tunneling asymmetries on Coulomb blockade edges and Kondo peaks in non-equilibrium transport through molecular quantum dots

Institut N´eel, CNRS et UJF, BP 166, 38042 Grenoble Cedex 9, France(Dated: May 18, 2015)We investigate theorerically the non-equilibrium transport through a molecular quantum dot as afunction of gate and bias voltage, taking into account the typical situation in molecular electronics.In this respect, our study includes asymmetries both in the capacitances and tunneling rates to thesource and drain electrodes, as well as an infinitely large charging energy on the molecule. Ourcalculations are based on the out-of-equilibrium Non-Crossing-Approximation (NCA), which is a re-liable technique in the regime under consideration. We find that Coulomb blockade edges and Kondopeaks display strong renormalization in their width and intensity as a function of these asymmetries,and that basic expectations from Coulomb blockade theory must be taken with care in general, ex-pecially when Kondo physics is at play. In order to help comparison of theory to experiments, wealso propose a simple phenomenological model which reproduces semi-quantitatively the Coulombblockade edges that were numerically computed from the NCA in all regimes of parameters.