Kondo regime in triangular arrangements of quantum dots: Molecular orbitals, interference and contact effects

TL;DR

This study investigates the transport properties of a triangular triple quantum dot system in the Kondo regime, revealing interference effects, molecular orbital influences, and contact-dependent conductance phenomena using advanced theoretical methods.

Contribution

It introduces a comprehensive analysis of a triple quantum dot in a triangular configuration, highlighting the impact of symmetry, interference, and contact effects on Kondo physics.

Findings

Interference effects significantly influence conductance when two leads are connected.

An S=1 Kondo effect emerges in perfect equilateral triangle configurations.

Adding a third lead causes amplitude leakage, modifying interference and conductance.

Abstract

Transport properties of an interacting triple quantum dot system coupled to three leads in a triangular geometry has been studied in the Kondo regime. Applying mean-field finite-U slave boson and embedded cluster approximations to the calculation of transport properties unveils a set of rich features associated to the high symmetry of this system. Results using both calculation techniques yield excellent overall agreement and provide additional insights into the physical behavior of this interesting geometry. In the case when just two current leads are connected to the three-dot system, interference effects between degenerate molecular orbitals are found to strongly affect the overall conductance. An S=1 Kondo effect is also shown to appear for the perfect equilateral triangle symmetry. The introduction of a third current lead results in an `amplitude leakage' phenomenon, akin to that appearing in beam splitters, which alters the interference effects and the overall conductance through the system.