Tuning Fano resonances by magnetic forces for electron transport through a quantum wire side-coupled to a quantum ring

TL;DR

This paper investigates how magnetic forces influence Fano resonances in electron transport through a quantum wire with a side-coupled quantum ring, revealing magnetic field-dependent resonance width modifications.

Contribution

It introduces a detailed two-dimensional model showing how magnetic forces alter Fano resonance widths via localized states with different current circulations.

Findings

Fano peaks occur at specific magnetic fields when localized states align with the Fermi level.

Resonance widths increase or decrease depending on the current circulation direction relative to the magnetic field.

Magnetic forces modify the coupling strength and lifetime of localized states, affecting electron transport.

Abstract

We consider electron transport in a quantum wire with a side-coupled quantum ring in a two-dimensional model that accounts for a finite width of the channels. We use the finite difference technique to solve the scattering problem as well as to determine the ring-localized states of the energy continuum. The backscattering probability exhibits Fano peaks for magnetic fields for which a ring-localized states appear at the Fermi level. We find that the width of the Fano resonances changes at high magnetic field. The width is increased (decreased) for resonant states with current circulation that produce the magnetic dipole moment that is parallel (antiparallel) to the external magnetic field. We indicate that the opposite behavior of Fano resonances due to localized states with clockwise and counterclockwise currents results from the magnetic forces which change the strength of their coupling to the channel and modify the lifetime of localized states.