Quantum current magnification in a multi-channel mesoscopic ring

TL;DR

This study investigates the robustness and characteristics of current magnification in multi-channel mesoscopic rings, revealing that it persists despite mode mixing and can be significantly larger than in single-channel systems.

Contribution

It demonstrates the persistence and enhancement of current magnification in multi-channel rings, and explores the effects of impurities and system-lead coupling on this phenomenon.

Findings

Current magnification is robust in multi-channel rings despite mode mixing.

Circulating currents can be much larger than in single-channel cases.

Impurities can either enhance or suppress the effect depending on parameters.

Abstract

We have studied the current magnification effect in a multi-channel open mesoscopic ring. We show that the current magnification effect is robust even in the presence of several propagating modes inspite of mode mixing and cancellation effects. The magnitude of circulating currents in the multi-channel regime can be much larger than that in a single channel case. Impurities can enhance or degrade the current magnification effect depending sensitively on the system parameters. Circulating currents are mostly associated with Fano resonances in the total transport current. We further show that system-lead coupling qualitatively changes the current magnification effect.