  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.
