Quantized magnetic confinement in quantum wires

TL;DR

This paper investigates how inhomogeneous magnetic fields create quantized conductance and magnetic confinement in ballistic quantum wires, revealing asymmetric magnetoconductance peaks and resonances due to diamagnetic shifts.

Contribution

It introduces the concept of magnetic confinement in quantum wires caused by inhomogeneous magnetic fields and explains the observed conductance features.

Findings

Quantized conductance steps occur when magnetic barrier and homogeneous field polarities match.

Asymmetric magnetoconductance peaks are observed as a function of the homogeneous magnetic field.

Resonances and shoulders appear in conductance when polarities are opposite, due to diamagnetic shifts.

Abstract

Ballistic quantum wires are exposed to longitudinal profiles of perpendicular magnetic fields composed of a spike (magnetic barrier) and a homogeneous part. An asymmetric magnetoconductance peak as a function of the homogeneous magnetic field is found, comprising quantized conductance steps in the interval where the homogeneous magnetic field and the magnetic barrier have identical polarities, and a characteristic shoulder with several resonances in the interval of opposite polarities. The observations are interpreted in terms of inhomogeneous diamagnetic shifts of the quantum wire modes leading to magnetic confinement.