Spin excitations in an all-organic double quantum dot molecule

TL;DR

This paper reports the realization of a strongly coupled all-organic double quantum dot molecule, observing spin excitations and Kondo effects, revealing competing magnetic interactions within the system.

Contribution

It introduces an all-organic double quantum dot with tunable magnetic interactions, demonstrating spin excitations and Kondo phenomena in a single molecule.

Findings

Observation of spin-1/2 Kondo effect in odd occupation

Detection of Kondo-enhanced low-energy excitations in even occupation

Variation of ground state between singlet and triplet in different samples

Abstract

We realize a strongly coupled double quantum dot in a single all-organic molecule by introducing a non-conjugated bridge in between two identical conjugated moieties. Spin-1/2 Kondo and Kondo enhanced low-energy excitations for respectively the odd and even electron occupation are observed in off-resonant transport. The ground state in the even occupation can be the singlet or the triplet state varying between samples. This observation suggests that both anti-ferromagnetic and ferromagnetic interactions between spins are of the same order of magnitude.