Abstract
We evaluate the non-equilibrium single particle Green's functions in the steady state of the interacting resonant level model (IRLM) under the effect of an applied bias voltage. Employing the so-called auxiliary master equation approach, we present accurate nonperturbative results for the non-equilibrium spectral and effective distribution functions, as well as for the current-voltage characteristics. We find a drastic change of these spectral properties between the regimes of low and high bias voltages and discuss the relation of these changes to the negative differential conductance (NDC), a prominent feature in the non-equilibrium IRLM. The anomalous evolution of the distribution function next to the impurity shown by our calculations suggests a mechanism whereby the impurity gets effectively decoupled from the leads at voltages where the NDC sets in, in agreement with previous renormalization group approaches. This scenario is qualitatively confirmed by a Hartree-Fock treatment of the model.
Highlights
Transport through nanodevices such as molecular junctions or quantum dots has become of great interest in the past due to the potential application of these systems as new types of electronic components [1,2]
A prototypical model exhibiting a negative differential conductance (NDC) is the so-called interacting resonant level model (IRLM), a simplistic model featuring a two-level quantum dot connected to leads used to study the interplay of quantum fluctuations and electronic correlations in the setting of quantum impurity problems
We evaluate nonequilibrium Green’s functions (NEGFs) of the IRLM in order to investigate their connection with the NDC and how the spectral and effective distribution functions evolve in terms of the bias voltage
Summary
Transport through nanodevices such as molecular junctions or quantum dots has become of great interest in the past due to the potential application of these systems as new types of electronic components [1,2]. The working principle of such components is entailed in their current-voltage (I-V ) characteristic. In some situations this can display nonmonotonic behavior, usually referred to as negative differential conductance (NDC), a peculiar effect that is intriguing by itself and most useful in potential applications [3,4,5,6,7]. A prototypical model exhibiting a NDC is the so-called interacting resonant level model (IRLM), a simplistic model featuring a two-level quantum dot connected to leads used to study the interplay of quantum fluctuations and electronic correlations in the setting of quantum impurity problems. Introduced by Vigman and Finkelstein [8] in the (equilibrium) context of the Kondo problem, the IRLM in nonequilibrium has received increasing attention over the last decade after the discovery of an analytic expression for the I-V characteristic [9] in the so-called scaling regime and for a special value of the interaction, referred to as the self-dual point of the IRLM
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