Singlet-Triplet Kondo Effect in Blatter Radical Molecular Junctions: Zero-bias Anomalies and Magnetoresistance

TL;DR

This study demonstrates the manifestation of the singlet-triplet Kondo effect and magnetoresistance in single-molecule junctions of the Blatter radical, revealing its potential for spintronic applications and the influence of molecular configuration on transport properties.

Contribution

It provides experimental evidence of Kondo resonances and magnetoresistance in Blatter radical junctions, highlighting the molecule's open-shell nature in electronic transport.

Findings

Observation of zero-bias Kondo peaks in conductance

High negative magnetoresistance without zero-bias peaks

Evidence of singlet-triplet Kondo effect in molecular junctions

Abstract

The Blatter radical has been suggested as a building block in future molecular spintronic devices due to its radical character and expected long-spin lifetime. However, whether and how the radical character manifests itself in the charge transport and magnetotransport properties seems to depend on the environment or has not yet been studied. Here, we investigate single-molecule junctions of the Blatter radical molecule in a mechanically controlled break junction device at low temperature. Differential conductance spectroscopy on individual junctions shows two types of zero-bias anomalies attributed to Kondo resonances revealing the ability to retain the open-shell nature of the radical molecule in a two-terminal device. Additionally, a high negative magnetoresistance is also observed in junctions without showing a zero-bias peak. We posit that the high negative magnetoresistance is due to the effect of a singlet-triplet Kondo effect under magnetic field originating from a double-quantum-dot system consisting of a Blatter radical molecule with a strong correlation to a second side-coupled molecule. Our findings not only provide the possibility of using the Blatter radical in a two-terminal system under cryogenic conditions but also reveal the magnetotransport properties emerging from different configurations of the molecule inside a junction.