Strongly correlated regimes in a double quantum-dot device

TL;DR

This paper investigates the complex transport behavior in a double quantum-dot system, revealing how inter-dot coupling and Kondo effects influence conductance across different temperature regimes.

Contribution

It introduces a detailed analysis of strongly correlated regimes in double quantum-dot devices using numerical and mean-field techniques, highlighting two-stage Kondo screening effects.

Findings

Non-monotonic conductance dependence on temperature and magnetic field.

Identification of two-stage Kondo screening process.

Enhanced conductance at intermediate temperatures due to Kondo correlations.

Abstract

The transport properties of a double quantum-dot device with one of the dots coupled to perfect conductors are analyzed using the numerical renormalization group technique and slave-boson mean-field theory. The coupling between the dots strongly influences the transport through the system leading to a non-monotonic dependence of the conductance as a function of the temperature and the magnetic field. For small inter-dot coupling and parameters such that both dots are in the Kondo regime, there is a two-stage screening of the dot's magnetic moments that is reflected in the conductance. In an intermediate temperature regime Kondo correlations develop on one of the dots and the conductance is enhanced. At low temperatures the Kondo effect takes place on the second dot leading to a singlet ground state in which the conductance is strongly suppressed.