On the Magnetic Nature of Quantum Point Contacts

TL;DR

This paper models a quantum point contact to show how electron-electron interactions induce magnetism, and analyzes how this affects conductance, supporting the Kondo effect's relevance in such systems.

Contribution

It introduces a model demonstrating magnetic moment formation in quantum point contacts due to electron correlations and links this to conductance behavior and the Kondo effect.

Findings

Magnetic moments are generated in quantum point contacts by electron-electron interactions.

The conductance temperature dependence aligns with experimental observations.

Supports the presence of the Kondo effect in quantum point contacts.

Abstract

We present results for a model that describes a quantum point contact. We show how electron-electron correlations, within the unrestricted Hartree-Fock approximation, generate a magnetic moment in the point contact. Having characterized the magnetic structure of the contact, we map the problem onto a simple one-channel model and calculate the temperature dependence of the conductance for different gate voltages. Our results are in good agreement with experimental results obtained in GaAs devices and support the idea of Kondo effect in these systems.