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

Abstract

We investigate theorerically the non-equilibrium transport through a molecular quantum dot as a function 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 the source and drain electrodes, as well as an infinitely large charging energy on the molecule. Our calculations are based on the out-of-equilibrium Non-Crossing-Approximation (NCA), which is a reliable technique in the regime under consideration. We find that Coulomb blockade edges and Kondo peaks 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, expecially when Kondo physics is at play. In order to help comparison of theory to experiments, we also propose a simple phenomenological model which reproduces semi-quantitatively the Coulomb blockade edges that were numerically computed from the NCA in all regimes of parameters.

9 pages, 8 figures

References in corpus (8)

• Molecular Transport Junctions: Vibrational Effects
• Supramolecular Spin Valves
• Mechanical Control of Spin States in Spin-1 Molecules and the Underscreened Kondo Effect
• Kondo effect in quantum dots
• Experimental Evidence for Quantum Interference and Vibrationally Induced Decoherence in Single-Molecule Junctions
• Tuning the Kondo effect with a mechanically controllable break junction
• Nonequilibrium Singlet-Triplet Kondo Effect in Carbon Nanotubes
• Nonequilibrium self-energies, Ng approach and heat current of a nanodevice for small bias voltage and temperature

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• Magnetic Field Universality of the Kondo Effect Revealed by Thermocurrent Spectroscopy
• Quantifying the leading role of the surface state in the Kondo effect of Co/Ag(111)
• Restoring the SU(4) Kondo regime in a double quantum dot system
• Relation between width of the zero-bias anomaly and Kondo temperaure in transport measurements through correlated quantum dots: Effect of asymmetric coupling to the leads
• Non-linear charge and energy dynamics of an adiabatically driven interacting quantum dot
• Replicas of the Kondo peak due to electron-vibration interaction in molecular transport properties
• Theory of differential conductance of Co on Cu(111) including Co s and d orbitals, and surface and bulk Cu states
• Width of the charge-transfer peak in the SU(N) impurity Anderson model and its relevance to non-equilibrium transport
• Scaling of conductance through quantum dots with magnetic field
• Leading temperature dependence of the conductance in Kondo-correlated quantum dots
• Kondo temperature when the Fermi level is near a step in the conduction density of states
• Kondo physics of magnetic adatoms on metallic surfaces when the onset of the surface conduction density of states crosses the Fermi level