  One promising route toward encoding information is to utilize the two stable
electronic states of a spin crossover molecule. However, while this property is
clearly manifested in transport across single molecule junctions, evidence
linking charge transport across a solid-state device to the molecular film's
spin state has thus far remained indirect. To establish this link, we deploy
materials-centric and device-centric operando experiments involving X-ray
absorption spectroscopy. We find a correlation between the temperature
dependencies of the junction resistance and the Fe spin state within the
device's Fe(bpz)2(phen) molecular film. We also factually observe that the Fe
molecular site mediates charge transport. Our dual operando studies reveal that
transport involves a subset of molecules within an electronically heterogeneous
spin crossover film. Our work confers an insight that substantially improves
the state-of-the-art regarding spin crossover-based devices, thanks to a
methodology that can benefit device studies of other next-generation molecular
compounds.
