Single impurity Anderson model out of equilibrium: A two-particle semi-analytic approach

TL;DR

This paper introduces a semi-analytic two-particle approach to study the non-equilibrium Anderson impurity model, successfully capturing key transport phenomena and eliminating unphysical artifacts in the calculations.

Contribution

It develops a novel semi-analytic method based on reduced parquet equations to accurately treat spectral and thermodynamic properties of the Anderson model out of equilibrium.

Findings

Reproduces three transport regimes with increasing temperature.

Eliminates unphysical hysteresis in current-voltage characteristics.

Shows bias voltage destroys Kondo peak similarly to temperature.

Abstract

We apply a two-particle semi-analytic approach to a single Anderson impurity attached to two biased metallic leads. The theory is based on reduced parquet equations justified in critical regions of singularities in the Bethe-Salpeter equations. It offers a way to treat one-particle and two-particle thermodynamic and spectral quantities on the same footing. The two-particle vertices are appropriately renormalized so that spurious transitions into the magnetic state of the weak-coupling approximations are suppressed. The unphysical hysteresis loop in the current-voltage characteristics is thereby eliminated. Furthermore, in the linear response regime, we qualitatively reproduce the three transport regimes with the increasing temperature: from the Kondo resonant tunneling through the Coulomb blockade regime up to a sequential tunneling regime. Far from equilibrium, we find that the bias plays a similar role as the temperature in destroying the Kondo resonant peak when the corresponding energy scale is comparable with the Kondo temperature. Besides that, the applied voltage in low bias is shown to develop spectral peaks around the lead chemical potentials as observed in previous theoretical and experimental studies.