Tunneling through triple quantum dots with mirror symmetry

TL;DR

This paper investigates how mirror symmetry in triple quantum dots influences the Kondo effect, revealing conditions where it is suppressed or altered due to geometrical and electron occupation factors.

Contribution

It demonstrates the suppression of the Kondo effect in symmetric triple quantum dots under specific electron occupations and geometries, highlighting the role of symmetry in quantum transport.

Findings

Ferromagnetic indirect exchange in N=3 triple quantum dots

Absence of zero-bias anomaly at N=1 in three-terminal geometry

Symmetry-dependent suppression of the Kondo effect

Abstract

Indirect exchange interaction between itinerant electrons and nano-structures with non-trivial geometrical configurations manifests a plethora of unexpected results. These configurations can be realized either in quantum dots with several potential valleys or in real complex molecules with strong correlations. Here we demonstrate that the Kondo effect may be suppressed under certain conditions in triple quantum dots with mirror symmetry at odd electron occupation. First, we show that the indirect exchange has ferromagnetic sign in the ground state of triple quantum dot in a two-terminal cross geometry for electron occupation N=3. Second, we show that for electron occupation N=1 in three-terminal fork geometry the zero-bias anomaly in the tunnel conductance is absent (despite the presence of Kondo screening) due to special symmetry of the dot wave function.