Persistent currents in mesoscopic rings with a quantum dot

TL;DR

This paper investigates how persistent currents in mesoscopic rings with embedded quantum dots are affected by temperature, broadening, and ring size, revealing suppression effects related to the Kondo regime and system parameters.

Contribution

It provides a detailed calculation of persistent currents using the Anderson model in the Kondo regime, highlighting the influence of temperature, broadening, and ring size on current behavior.

Findings

Persistent current approaches ideal ring value for large L/xi at T=delta=0.

Current is suppressed for side-coupled quantum dots.

Increasing T or delta suppresses current depending on flux and level spacing.

Abstract

Using the Anderson model in the Kondo regime, we calculate the persistent current j in a ring with an embedded quantum dot (QD) as a function of the Aharonov-Bohm flux Phi for different ring length L, temperature T and broadening of the conduction states delta . For T=delta =0 and L >> xi, where xi is the Kondo screening length, Lj tends to the value for a non interacting ideal ring, while it is suppressed for a side coupled QD. For any L/xi, Lj is also suppressed when either T or delta increase above a fraction of the level spacing which depends on Phi.