Conductance anomalies and the extended Anderson model for nearly perfect quantum wires

TL;DR

This paper explains conductance anomalies in nearly perfect quantum wires through singlet and triplet electron resonances, using an extended Anderson model to account for many-body effects like the Kondo resonance.

Contribution

It introduces a universal explanation for conductance anomalies in weakly confined quantum wires via an extended Anderson model framework.

Findings

Anomalies are linked to singlet and triplet resonances.

The behavior is robust across various wire geometries.

The model predicts Kondo physics at low temperatures.

Abstract

Anomalies near the conductance threshold of nearly perfect semiconductor quantum wires are explained in terms of singlet and triplet resonances of conduction electrons with a single weakly-bound electron in the wire. This is shown to be a universal effect for a wide range of situations in which the effective single-electron confinement is weak. The robustness of this generic behavior is investigated numerically for a wide range of shapes and sizes of cylindrical wires with a bulge. The dependence on gate voltage, source-drain voltage and magnetic field is discussed within the framework of an extended Hubbard model. This model is mapped onto an extended Anderson model, which in the limit of low temperatures is expected to lead to Kondo resonance physics and pronounced many-body effects.