Destructive quantum interference in transport through molecules with electron–electron and electron-vibration interactions

Abstract

We study the transport through a molecular junction exhibiting interference effects. We show that these effects can still be observed in the presence of molecular vibrations if Coulomb repulsion is taken into account. In the Kondo regime, the conductance of the junction can be changed by several orders of magnitude by tuning the levels of the molecule, or displacing a contact between two atoms, from nearly perfect destructive interference to values of the order of 2e 2 /h expected in Kondo systems. We also show that this large conductance change is robust for reasonable temperatures and voltages for symmetric and asymmetric tunnel couplings between the source-drain electrodes and the molecular orbitals. This is relevant for the development of quantum interference effect transistors based on molecular junctions.

Heat current across a capacitively coupled double quantum dot

“…The NCA has being successfully applied to the study of a variety of systems such as C 60 molecules displaying a quantum phase transition, 48,81 , a nanoscale Si transistor, 52 twolevel quantum dots, 82 and the interplay between vibronic effects and the Kondo effect. 39,83 In spite of this success, the NCA has some limitations at very low temperatures (below ∼ 0.1T K ). For example, it does not satisfy accurately the Friedel sum rule at zero temperature.…”

“…The mapping is explained in detail in Ref. 39 and applies also for other molecular quantum dots with destructive interference. The model is also equivalent to a spinfull model for one dot in which electrons with spin up can only hop to the left lead and electrons with spin down can only hop to the right lead (naturally the leads can be interchanged).…”

“…This model is equivalent to that of transport between two levels with destructive interference (DESINT) under high magnetic fields (the "DESINT model"). 39 For example if a benzene molecule is doped with one electron or one hole, the many-body ground state has spin and orbital degeneracy. If the molecule is connected to one lead at an atom and the other lead is connected perpendicular to the first one so that it is coupled equally to a first and second nearest neighbor of the first atom, there is a linear combination of the many-body states that couples only to one lead and the other combination to the opposite lead.…”

Charge density wave breakdown in a heterostructure with electron-phonon coupling

“…Further, applying a thermal gradient to the system would allow for the study of thermal transport through such quantum structures, see, e.g., Refs. [39][40][41][121][122][123]. Lastly, being able to compute a current-voltage diagram for the CDW phase, its dynamics, and its properties at finite temperature would be of great interest, e.g., in the context of recent experiments [8,25,27].…”