Conductance scaling in Kondo correlated quantum dots: role of level asymmetry and charging energy

TL;DR

This study explores how level asymmetry and charging energy influence the conductance scaling in Kondo-correlated quantum dots, using numerical and perturbative methods to identify universal behavior and deviations.

Contribution

It provides a detailed analysis of conductance scaling in quantum dots, highlighting the effects of asymmetry and Coulomb interactions with numerical and analytical approaches.

Findings

Universal Kondo scaling observed near particle-hole symmetry

Deviations increase with level asymmetry and lower charging energy

Excellent agreement between NRG and renormalized perturbation theory at symmetry

Abstract

The low temperature electrical conductance through correlated quantum dots provides a sensitive probe of the physics (e.g., of Fermi-liquid vs non-Fermi-liquid behavior) of such systems. Here, we investigate the role of level asymmetry (gate voltage) and local Coulomb repulsion (charging energy) on the low temperature and low field scaling properties of the linear conductance of a quantum dot described by the single level Anderson impurity model. We use the numerical renormalization group to quantify the regime of gate voltages and charging energies where universal Kondo scaling may be observed and also quantify the deviations from this universal behavior with increasing gate voltage away from the Kondo regime and with decreasing charging energy. We also compare our results with those from a recently developed method for linear and non-linear transport, which is based on renormalized perturbation theory using dual fermions, finding excellent agreement at particle-hole symmetry and for all charging energies and reasonable agreement at small finite level asymmetry. Our results could be a useful guide for detailed experiments on conductance scaling in semiconductor and molecular quantum dots exhibiting the Kondo effect.