Effect of impurity on current magnification property of mesoscopic open rings

TL;DR

This paper investigates how impurities affect current magnification in mesoscopic open rings, revealing that impurities can enhance circulating currents, contrasting with their known effect in closed rings with magnetic flux.

Contribution

It demonstrates that impurities can significantly increase current magnification in open mesoscopic rings, a novel finding compared to their usual suppressive role in closed rings.

Findings

Impurities can enhance circulating currents in open rings.

Current magnification depends on Fermi energy range.

Contrasts with impurity effects in closed rings with magnetic flux.

Abstract

We have considered an open system consisting of a metallic ring coupled to two electron reservoirs. We have recently shown that in the presence of a transport current, circulating currents can flow in such a ring even in the absence of magnetic field. This is related to the current magnification effect in the ring. In our present work we have studied the effect of impurity on the current magnification. We find that the presence of impurity can enhance the current magnification in the loop significantly and thus lead to large circulating currents in certain range of Fermi energies. This is in contrast to the known fact that impurities can only decrease the persistent currents in a closed ring in the presence of magnetic flux.